WOW! From failing to Excellent grades in such a short period of time. Sorry, I'm suspicious.
I started typing, then got complicated and started confusing myself. Let's make this REALLY simple. Isn't he on Celexa? Isn't this the medicine that you believe might be causing more intense, albeit rarer, outbursts? Isn't it possible that you will stop this medication, if you do feel that they are causing these more intense outbursts? If he does stop this medication, you will be back to square one. He needs an IEP.