Here are my suggestions as a teacher and a mom of a bipolar child and an ADHD child. First of all, I doubt that the doctors will diagnose a mood disorder at a young age. It was a stretch to get my son diagnosed at 12. Meanwhile, you need to check to see if the meds can be adjusted/changed to help him. There are many med choices and dosages that may help. Also, as already suggested, find a therapist who can help you and your child. Make sure the therapist really does work with children such as your child. I have found that some therapists just give a child a fun playtime instead of addressing the child's needs outside of therapy. As soon as my child started playing chess in therapy we quit that therapist. I can play games at home.
Good luck!
Bluemountains