What's the status of the Zoloft and the Wellbutrin? Both can cause or increase mood swings, including mania. Racing thoughts are a symptom of mania. If the Zyprexa has slowed that down but the ADs are still there, the mania will likely return.
Other possibility is that he is rapid cycling (defined as four or more mood swings in a year), possibly slowed down from ultra rapid cycling by the Lamictal. And don't forget, mood stabilizers don't always eliminate mood swings but sometimes only reduce the number of them.
Anyway you look at it, making a major change this close to the end of school is just stupid.
