Hello, let's try to understand this situation.
First of all, you need to consult with a neurologist. Since too active children are easily over-excited and start up from half a turn.
Secondly, the boy has conflicts with his peers, with his words they call him names. Be sure to go to a psychologist and find out all the causes of such conflicts and aggression.
Maybe he himself first begins to attract attention or, on the contrary, the children specifically provoke him, joke and scoff. Perhaps he has a lack of self-confidence, and in this way the son raises his self-esteem. The reasons may be many. It is necessary to help the child necessarily!
Regarding the section, talk with the coach, let him, as an authoritative person for children in boxing, tell you in what situations you can use your strength and technique, and when not. Only after finding out all the circumstances can you decide whether to continue visiting the section or not. But keep in mind, for a child, it can also be a trauma, if he likes this hobby and he enjoys and achieves pleasure.
All the best!