OP I'm sorry this is happening to you. My DS (now 9, happy) kept hearing (NOT from the teachers, but from the other children, aged 5-6) that he was a 'bad boy' who was 'being naughty' and it broke his heart. He even said "I'm a bad kid" and "people don't like me because I'm bad" - I know that you can imagine what that feels like.
In an ideal world we'd have a private 1:1 teacher for him, in a forest school, and he'd make his own way while moving constantly - but we live in this world, and instead, we got right up to the edge of school refusal, and then thankfully broke up for the summer.
That was the point we decided to try ADHD medication, and he now takes medicine every school day. At that point (basically when the medicine helped him sit still, listen, and complete basic tasks) everyone noticed what we already knew, which is that he's very clever. And he now has a few friends, and is top of the class in everything, and it's much, much easier. He's also high functioning autistic, so it's not plain-sailing, but without the ADHD medicine we'd have never got the autism diagnosis, because he's SO hyperactive that he couldn't be interviewed or complete tasks or talk to the diagnosing people.
Getting the medicine for him was not difficult but I lived in America at the time, and I do not know what it's like for you. I was terrified, would there be side effects, would it stunt his growth, etc etc - and it has been fine. The main side effect is that it kills his appetite, and he tends not to eat lunch, but have two suppers.
Over holidays and weekends we don't use it, and he eats tons and grows tons.
I am not saying "drug your child so people will like him" but if it's as bad as it was for my son, it could be the answer. As well as disrupting other children's learning (which I know he was, even with a 1:1 aid) he was barely learning anything himself because he just couldn't sit still long enough to hear, see, or do any activity.
He describes the medicine now as 'turning down the lightening in my head, so I can hear other things' or 'just making the noise easier.'
I was so worried about giving him medicine, but if he needed (say) glasses or a leg brace, I'd get them without a moment's concern. He needs this medicine in a similar way, to do the tasks a modern school asks him to do.