I had severe panic attacks in school to the point that I'd scream in front of my classmates and get up to run to the nurse. Needless to say, the kids call me "psycho." Often anxiety/panic attacks go along with mood disorders. I had both. medications have stopped my panic attacks (I take Paxil and Klonopin, but don't recommend these for children).
I would amend his IEP to say he can go to the nurse if he feels anxious. Often it's a matter of having a calm person there for you. I'd also tell him that caffeine can make it worse and maybe he should pass on Coke and drink Sprite. Caffeine would ALWAYS give me panic attacks. If you see a Psychiatrist, I would resist if he wants to put your child on stimulants because I tried them and, although everyone is different, just one day of Ritalin set off severe depression and anxiety for a year for me. You have to be careful with anxiety--the wrong medications can be lethal. The right ones can allow you to live a normal life. Great therapy for anxiety disorder is Cognitive Behavioral Therapy. Talk therapy didn't do squat for me, but CBT was magical. I still use it. Pick up Dr. David Burns book "Feeling Good" to have CBT explained to you. It changed my life. I'd have panic disorder, anxiety disorder and depression from as early as I could remember, and school and wide open spaces were both triggers for me. (One last thing: Again, although everyone is different, Prozac made me even more nervous. So did Zoloft).