Thanks for your feedback, everyone. Here is some more background:
My son is 9 years old, gifted intelligence, diagnosis of ADHD - type not specified, Pervasive Developmental Disorder (PDD)-not otherwise specified, and sensory processing disorder (SPD).
I am trying hard to keep him in a public magnet school that he has attended since Kindergarten. He is in 4th grade now, so next year will be his last in this school. There is a new administration in place this year that is less flexible and willing to work with us than what we've had in the past. I've already received a certified letter that his record is being reviewed for revocation of his school choice for next year. The letter requests a meeting with administration and they want me to sign some kind of contract. He's had a total of 4 days suspension so far, but is in the office probably 2X per week due to screaming / crying.
His issues are extremely loud and disruptive temper tantrums and physical aggression. His main triggers are any type of competition, especially sports, but also academic (most recent episode was triggered in music by failing to advance in "Recorder Karate"; He missed one word on a spelling test recently, and it took him 2.5 hours to calm down). He is under the care of a psychiatrist (as well as the behavioral therapist). He is taking Abilify and Guanfacine. We had quite a bit of success with these when he started taking them at the end of second grade, but now he is regressing to behaviors that he demonstrated prior to starting the medications, including the physical aggression, low frustration threshold, sleep disruption, and motor tics.
My goal in having him work with a therapist was to try to help him get the tools to be more assertive in social situations, and to better 'manage' his emotions, so that he will be ready for middle school in 18 months. I feel like the root of some of my son's issues is poor self-esteem, and I told the therapist this, but he isn't approaching my son from that direction at all.