Jen, we use Strattera to manage our DS's attention issues. It works well for us, without the ramped-up anxiety that the stimulant-class ADHD meds produce. He also takes a tiny dose of Celexa for anxiety, which radically improved his ability to cope in social situations like the ones you describe at school.
I'm glad you're seeking further evaluation, because meltdowns at school *are* stigmatizing. Is anyone at school teaching him to manage and diminish these? Ultimately he needs to learn strategies to be responsible for his own behavior.
I can't believe the school can't go to a system of choosing teams some other way. Letting the kids pick is barbaric. I know the gym teacher isn't sympathetic, but is there someone you trust there who could broach this to the gym teacher and/or principal? If they are committed to helping your DS, they shouldn't let this slide.
Hang in there,
DeeDee
