My son seems to have lost all enjoyment for things and doesn't want to go out or do anything

My son is 5, diagnosed ASD with anxiety related demand avoidance and severe sensory struggles.

When he first started school last September he was on a massively reduced timetable and based out of the nurture cabin - his behavior massively improved as he left nursery which he hated.

Fast forward to now and he's on 4 full days, still based out of the nurture cabin but is encouraged to the main class more - but all led by him. But his behavior has declined again, and his anxiety is through the roof. I know school is the problem and I'm going to tribunal to try and get him into a special school.

However, my main concern at the minute, behavior aside - is he just doesn't want to do anything, doesn't want to go outside, ride his bike, play with his cars, play with his brother - absolutely nothing. These are all things he previously really enjoyed. He will happily sit on his tablet all weekend (which is an internal debate of mine!). He looks so sad. He is also much more sensitive to his sensory triggers.

I don't know if he is in burnout? Should I just let him do nothing if he is in recovery time from school?

School have agreed to some changes to reduce the demand and overwhelm of school, so hopefully that will help but I'm assuming it will take time for me to see his overall anxiety reduce and wellbeing improve? We have a low demand approach at home already and it's at his lowest at the moment.

It just makes me so sad and I don't know the best approach, and it obviously impacts the whole family including his younger brother, as we don't go out and do family things like we did previously - and it was only ever walks and parks and things away from people!

Just after advice really about what could be going on for him and what is the best way to support him.

Thank you x