PIP Appeal Advice for Autistic Adult Son ?

My Son who is 23 now has been in receipt of DLA since his diagnosis back in 2006, He used to get Middle component for daily living and lower for mobility. He has recently been reassessed for PIP. He was refused after the assessment , and after the Mandatory reconsideration request.

We now face an appeal that I myself am not prepared for and don’t feel I even have the strength to take on, he scored zero for everything even though I have to do ‘everything’ for him, such as cooking, washing/drying his hair , even down to clipping his finger and toenails. Accompanying him to doctors/hairdressers. Prompting to wash, and asking for his clothes he has been wearing a week, looking at his bleeding Unbrushed teeth and smelling his bad breath and body odour.

I feel the assessment went badly because he answered questions he shouldn’t have with the wrong answers, and didn’t realise the consequences of just saying yes or no to shut the assessor up. He is very naive 

He has a small job at Sainsbury’s which he only has because I work there myself and got him the job. Without me he would cease to function, he does not leave the house aside from the 2 shifts a week he works, or socialise with anyone, he does not wash unless it is to go to work. He plays games all day and hides away in his room. He does not care or understand responsibility and I worry what will happen to him when I am not around anymore. He is very stubborn and will not try new things, does not like any change to routine. His mental age could be compared to a 13 year old boy. Him having this extra money would be a crutch for him that we need the security of.

The assessor reported he had good eye contact, even though She barely looked at him, she performed a mental state exam? How can she possibly know what is going on inside an autistic adults mind , their expressions often blank and emotionless. They were told how his disability affects him and they chose to ignore most of it and say ‘ I have decided you can’ even though I say he can’t ? How do you win such an argument? 

I feel so desperate because he looks ‘normal’ to the average persons. He travels too and from work with me , he cannot go out on his own and would not do so. Yet the assessor decided he can plan and follow the route of a journey unaided , even though he cannot ? And would not , he has not recently seen any specialists for autism, as it is a lifelong condition and not likely to change. I am worried I do not have enough evidence and don’t know where to begin to get any ? He received all the support in school and through college , could they offer any evidence? ,All I seem to have is my word that he is hard work and needs my help every day. And a diagnosis report from 2006. 

Any advice would be hugely appreciated , I now have about 3 days to complete the appeal forms and send it off as I’ve ignored it for over 2 weeks because I can’t cope. Thank you