10 year old daughter with extreme anger HELP

One thought, by "after" do you mean immediately after or the next day kind of "after".  If she's in meltdown due to well anything which may have overloaded her she'll be unlikely to be able to communicate that straight away, she'll have to recover from the melt down first.  She might be able to tell you in a calm moment a day later.

I would remember that the "smallest thing" is likely to be one small thing that has come on top of a bombardment of "small things" (which are in fact pretty big things for Autistic people) which she's had to endure all day.  What do school say?  Does this happen at school?  Often times Autistic girls spend all day holding in distress and anxiety due to sensory overloads, information processing and social exclusions and /or the strain of socially masking, and then explode the minute they are home precisely because it's a safer environment.

Hi Dawn

thank you for responding. school have said she can literally go from 0 to 100, but can mostly bring herself back down with breathing techniques and grounding. She has been having more outbursts at school with one or 2 of them being violent (arms and legs flailing, screaming etc) 

Hi Dawn

thank you for responding. school have said she can literally go from 0 to 100, but can mostly bring herself back down with breathing techniques and grounding. She has been having more outbursts at school with one or 2 of them being violent (arms and legs flailing, screaming etc) 

Aside from general overload provoking melt down, the 0 to 100 can also be to do with problems in the interoception, in other words whereas most people can recognise that they feel angry and check that before it explodes, some Autistic people can't do that because the sensations which provide the physiological cues to emotional feeling or bodily need are confusing to them or even not felt, or felt too strongly.  She may not even recognise that she is angry until she's already at 100.  It can also mean that she would find it difficult to attach words to describe what she is feeling or was feeling at the time.

If she's struggling to tell you what's behind it, try keeping some notes of the incidents, you might notice a pattern of triggers - perhaps sensory, perhaps social or something else, which may give you a few clues as to what needs to be adjusted.  The needed change might be the environment rather than her.