Dave, there's a chance that what you call a "seizure", and during which you felt so hellish, might have been a panic attack. Though I still would not rule out the possibility of it being some kind of seizure either. At some point, you mentioned you had had a panic attack prior to your starting taking meds. Did it feel similar to what you went through most recently?
What else did the doctor say? When you described to him/her this most recent experience, it was him/her who said it was a "seizure"? Also, what did the doctor say about the cause of this reaction?
Had you had any extra life-related stressors in the last couple of days? Your system in WD/post-adverse reaction is *so* taxed that it may have resulted in such a reaction.