S.S.
I agree about the karate suggestion. My five-year-old has low self esteem that has really turned around since he has been in karate. The coach is very concerned about his success and helps whenever he can. My son even took third place at the in house tournament...and he was the smallest one there. Karate has really helped him. I can't say enough about it.
Good luck...I know it is hard. I hope things work out for you!