Well, since you did not specify what sort of behavioral issues he is having, it’s a bit hard, but before you walk down the road of assuming he has all sorts of labeled problems, know that there are certain ages when kids start some behaviors; they become aware of the pecking order and if they’re not near the top of it; and more. Sit and talk with him about what is going on. Listen to his perspective and try to remember what it felt like to be his age. You need to teach her how to solve his problems, not become one of those helicopter parents who jumps in so often that it literally cripples his ability to develop successful social interactions.
My daughter started having problems in school which was when we discovered she had a learning disability and couldn’t keep up. We had to meet with her teachers, develop a new plan and do a lot of home tutoring. However, in the end she graduated from college with honors, so all the work was totally worth it.