It could be a combination of AD(H)D and depression. When I was that age, I certainly tried my hardest to hide depression issues from my parents. I would do whatever I could to keep myself from the things that were making me depressed, and while it really helped me deal with the depression aspect of things... I was still completely unable to do all my work. I think seeing a doctor would be a great idea for your son. As far as kids picking on him, I don't know what to tell you there. I've been picked on before, but it never *really* got to me. As long as he has at least some friends who don't pick on him he should be okay