Behavior issues in my 11 year old

Patient: I have a son of 11 that is have issues at school with his behavior, he has always been full of energy since the day he could walk constantly on the go with some issues with his temper and behavior even then. I found it difficult to take him places without people judging my parenting even though ~I was going by all the advice I could get my hands on.His behavior at school wasn’t an issue until he was around 8 years and the teachers have since constantly complained about him shouting out, hiding under cupboards and desks, sometimes scratching himself with pencils and strangling himself. His behavior can be maintained but it takes more attention than most teachers can or are willing to give. He can behave in a great manner with lots of help and positive reinforcement but feel like it’s a losing battle at school.Any advice on how to help him would be gratefully accepted.