Just because school have done a screening for ADHD doesn’t mean dc
doesn’t have ADHD.
if your dc was removed from class 50x for being disruptive during a 39 week school year, either he is incredibly badly behaved (is he really that bad? Seems unlikely?) he is in the wrong school or there is something further that needs investigating i.e. ADHD or bullying or something like nobody has noticed he can’t read & he can’t follow what’s going on in class
I would investigate adhd assessment with your GP & also by reading about it, the effects & things that can be done to help him in the meantime as well.
waiting lists can be long - I don’t know if right to choose applies to adhd assessments but it’s worth exploring that too, if you decide to go down that route
there are loads of ways to find out more yourself & find ways of helping him. Sitting him in a classroom on his own is unlikely I think to help (I’m not an expert).
Schools are the biggest gaslighters ever when it comes to neurodiverse children ime so I suggest you need to get reading, listening and googling but as the parent of a neurodiverse child & with 2 close friends with similar - all 3 kids have really good support now and mothers who have never worked as hard for anything as the support they dc’s (now) get in their respective schools
your dc’s school will have a SENCO - they may or may not be good but I’d do some reading around & inform myself and start with a conversation with them but do you have any friends/friends of friends who have a child with adhd? I’d also reach out to my network for help
I would never have believed some of the nonsense that comes out of some people’s mouths in schools from people who are otherwise respected, experienced professionals but that’s where we are so it’s up to us to advocate for our dcs. Good luck x