Maybe it is just a phase and part of growing up. I was a holy terror in school and at home for about three years (ages nine to 12). Then I got over it. One of my children was a pain in the neck around the same age. He got over it as well. Misbehavior is not necessarily abnormal.
I would suggest getting, " "The ADD/ ADhD Answer book." , by Susan Ashley." It has lots of ideas that will help you. Good Luck