NOBODY WILL LISTEN

now the food issue maybe because he perhaps had a case of uncooked or bad tasting of that food before, that just puts anyone off their appetite for it in the future even if they liked it before... just having one that was off, your memory of that food is your last and strongest, if the last memory of that food was it tasking horrible or being off or making you feel sick, then youd never have that food again even if that was a one off, you dont wanna risk that... i think thats why i turned into a fussy eater as a kid, because it was always horrible or off... infact thats why i dont eat cereal or drink milk anymore as most of the time from what i remember the milk was always off, and one time with cheerios there was a moth infestation in it with thousands of moths in but i ate a mouthful because i didnt have my glasses on to see it  clearly at the time. put me off cheerios forever.

as for things that can hurt, i notice i have a very strong tolerance to blunt force trauma and can take blunt damage and ignore it easily.... blunt damage is pretty ok to put up with and even soothing.... but cutting damage, such as a paper cut... yeah that hurts lol it maybe the same with your kid. just super resilient and even liking blunt trauma... but super sensitive to cutting type damage. which feels aweful as you feel it slide through your skin.

Being a parent, I know how much we desire to connect with our kids. You are their best advocate!  Hopefully this will help:

These kids have difficulty with Filtering. EVERYTHING is intimate, invasive, arresting. A non-consensual hug can feel like sexual abuse. 

The Autistic brain is wired such that it cannot Filter incoming signals like non-autistic peers. And so anything which is invasive, unkind, non-human friendly, inconsiderate, is Sensed with a great deal of intensity. 

The second Element which is a different experience is our heightened ability to focus or a Flow -State. Have a look at this site: https://monotropism.org And so harsh, smash-cut interruptions will be like waking a sleepwalker. To an Autistic, they will Genuinely Feel Like Waterboarding. 

In modern society, sensory torture is illegal. Look up White Torture, Sensory Deprivation and Interrogation, Sonic Weaponry and Enhanced Interrogation Techniques - sensory overload (bright lights or strobe lights, loud noises or music).

However, Autistics will have a daily experience of these to some level, or some degree. Modern society is such that:

Clothing is made from Petroleum and IS plastic. It's called Polyester or Nylon and if it catches fire, melts onto the skin. It is like wearing paint. And we all know the horror of what happened to the Bond girl who was painted gold. 

Our sense of smell is supposed to be used to smell danger: it is used by foragers to decipher between poisonous and edible mushrooms. To identify an electrical fire or lamb which has gone off. Some can smell formaldehyde and even Covid! Now, currently it's still legal for companies to manufacture scented candles, cleaning agents and air 'fresheners' with VOCs which are incredibly harmful. A scent is made up of micro particulates which interact with the lungs and the gut. https://oneseedperfumes.com/blogs/news/world-environment-day-why-your-perfume-may-be-polluting-more-than-your-car

Sounds: There's human-friendly sound such as natural acoustics out doors or in a well treated space and then there's non human-friendly sounds such as electrical wires buzzing, reverberations from cafeterias and other terrible structures which no thought or intention around acoustics went into. Now, your child might have the capacity to explain the physics of this to you once they're 18 or 28. But not yet. For now, trust that they are tapped into the natural order of the world quite well. Hand Dryers have been clocked exceeding a level that is damaging/deafening to the human ear. 

As for food, be mindful of Gut issues. One doesn't need much. Just the right nutrition. If all they will eat is a chicken, buy organic. Instead of worrying about a buffet, simply spend time making the breaded stuff and find a good mixture they enjoy. You could try a Very Plain gluten free flour, organic milk and add in mineral rich salt (like charcoal, clay or natural sea salt), don't force them to eat vegetables which adults might need due to no longer regenerating like young children do. One fruit will do. Jane Goodall lived off of Bananas for months at a time and lived a long life. This should make your life easy and if they like the breaded ingredients, perhaps you can add honey (with good B vitamins) or maple syrup (which has iron) or use similar ingredients to make a no-sugar-needed crumble. Natural sweetness plus lemon work well I've found. But given I'm allergic to grains/cereals, and sugar cane is a grass, I've found it easier to digest honey, coconut, maple or date sugar. Artificial Sweeteners are not human-friendly.

Back to the main two complications:

Interruption severs a flow-state and as a result, doing more than One-Thing-At-A-Time is a Health and Safety Issue. 

We cannot dull our senses like Non-Autistics. 

But any rules of good manners will suggest it's unkind to interrupt and unkind to overwhelm. :) 

Crikey!

You could have written that about our son too. He is exactly the same.
Following not much help from School - we were told our son "Would grow out of it" and there was "Nothing to worry about" ,the old fave "He's fine in school" and ever our Parenting Capabilities were questioned.

Like you, we did our own research and read heavily on just about everything we could do find on Autism, ADHD, ODD, Depression, etc, etc.
And then we came across PDA - and had the same 'lightbulb' moment. And everything seemed to fit.

So - we have another meeting with SENCO at his Primary School - who told us (quote) "You don't become an expert in mental health by reading stuff off the internet" and then went on to tell us that she had never even heard of PDA.
As far as she was concerned - he was fine in school; and that was that.

We confronted her with 3 years worth of daily diaries - which showed chapter & verse, every single day, the meltdowns, the triggers, the good days and in an "edited highlights" version - it showed a clear pattern in the changes in our sons Anxiety and of course his Moods and Meltdowns.
This couldn't be argued with - given the Mood swings and increased anxiety seemed to be around changes to routine, the unknown or something that could be counted as sensory (noise/colours etc).

Upon moving up to the next year, within the first week of School - the Class teacher spotted Autistic Traits and a possible Anxiety Issue. So, literally she bent over backwards to help us - she provided a weekly timetable in advance - so our son knew what was happening.
She updated us (via email) daily on any possible triggers in school and also helped push for help.

By this time, our son had been masking this for the best part of 5 years.

We had no end of School Refusal mornings - where on many occasions - he was arriving at school 3 or 4 hours late - having locked himseld in the bathroom.

On one occasion, the SENCO and Attendance officer visited the house (after we had spent 2 hours calming him down) - which made matters worse. So - that day, instead of being an hour late for school - he went into shutdown and ended up with the day off school to recover.

The SENCO and Attendance officer had to leave, after 5 minutes as the contents of the bathroom were hurled down the stairs at them. The left, telling us "We'd better leave, as we are not helping" (No Sh*t!)

By this time, we had referred our some to CAHMS to hopefully get some answers/diagnosis and he was put on the Autism Assessment Pathway.

The SENCO finally brought in external help - to suggest interventions at School.
We met with The Local Authority Autism Awareness team  and our sons class teacher - and a support package was drawn up (nothing that cost anything, just simple things) - and the LA Autism Awareness team, I cannot fault - they did a lot, and provided (as did this website!) a lot of very helpful information.

Yet the SENCO still thought those interventions were too much - and not many got put in place.

Then along came something called Covid.

Upon the return to school - it was our sons last year in Primary School - and his anxiety levels were at an all time high (as the move the Comp was on the horizon).

His new class teacher was amazing, The SENCO was still on the "There's nothing wrong" thing.
At the same time, our son recieved his Autism Diagnosis - though they didn't recognise PDA.
The School however continued with their basic interventions.

The transition period for the move the Comp never happened; apart from 2 weeks before the end of term - where he was chucked in at the deep end with no interventions (the SENCO hadn't passed his file on to the school).

So - where are we now....?

Our Son started comp in September 2021 - with no proper things in place to help him.
So naturally,, we had the runs of School Refusal, Violent Meltdowns and threats from the school for "no attendance".
What the school did offer - in our opinion, was too little, too late - given he had spent the last 8 years masking is anxieties and exploding when he got home.

He lasted a total of 6 weeks before he came home from school in early October and broke down. Burned out.

That was his last say in Full Time education; we removed him from the school register and he is now homeschooled.

In our situation - he has changed, become a different person - and enjoys his school work.
As he is very "hands on" we concentrate on hands on & practical education - so he can do Maths - without filling out sheets full of sums (besides - I am dreadful at maths!!!).

He has control over his "timetable" when he does it, and how he does it. He may not feel like working on a (say) Tuesday, but instead will do something on a Sunday etc.

We still get the metldowns at times - but they seem to be through frustration.
Also - the way things are presented and worded make a huge difference.

For instance "Tidy your room" would almost certainly trigger a meltdown or he'd just ignore you.

Saying something like "I need a hand doing some tidying, can anyone help" - chances are he'd jump up, offer to help and even go and do his room!!

Apologies for the War & Peace on this; but that's our experience so far!

You aren't on your own.

Wait till he gets to school and starts getting into constant battles with his teachers. Then it will be much harder for people to deny there is a problem. Especially since you've been saying so for a long time now and it is therefor not just some excuse you've come up with for his behaviour.

Not for autism but the school SENCO told me my son isn't dyslexic as he can read and isn't dyspraxic as he plays sport (badly!). Private assessments say he has both, and actually he is super clever and uses certain skills, particularly visual/spatial to cover the dyslexia - he learnt to sight read not with phonics for example. I know a couple of families who just got their boys diagnosed with ASD at about age 7 despite in both cases all the professionals agreeing that was the right diagnosis for years before. Unfortunately the only way to speed up the process is to pay privately, which for ASD for a child I think you are looking at about £1500 - 2000. Its a big investment but could save a lot of pain in the long run if you can afford it, although he might have to be a bit older - you don't say how old he is now and if he is at school/nursery as one of the key factors is how they respond to different environments. We paid about £1200 for my son's assessments but in the end it worked out really well - he would have had years without support if we hadn't been able to pay. I suspect he has ASD too as there is a strong family history but at the moment he is coping relatively well, if needed I would spend all our savings on an ASD assessment as I know he would never be high enough priority to reach the top of the list for NHS assessment. If they are learning and coping OK - even if not well - then there are always too many others that are higher priority.