I agree with mammo, he needs professional help. The only thing that you can do at home right now is to get him that help. Basically, they are saying that your son probably has ADHD. A good book that deals with this is, "The ADD/ ADHD Answer book," by Susan Ashley. There are things that you can do at home to help him with the fighting and they are detailed in the book. A child psychologist is a good choice, a child psychiatrist would be even better. Good luck.
Yes, take your son to see a child psychologist and go from there.