R.M.
I would vote for another visit to the doctor...and possibly a few sessions with a child psychologist to get to the root of what is causing this. Let the doctor rule out physical causes first....then start thinking about what psychological issues may be contributing to this. What is the relationship between the young man and his family??? Is this a bid for attention...or a way of proving that HE is in charge??? Since it is happening at school too...maybe the school counselor could be of some help.