Head in my hands symptoms and conditions

I have been on topomax for nearly a year and have many of the same problems you guys have but a new one has popped up on me that scared the shit outta me and no one can seem to figure out what is causing it.
During sex just before orgasm my brain felt like it was going to explode!!
All I could do was hold my head in my hands and roll on the bed. this pain lasted for almost 8 hours. the next day i felt fine and went motorcycle riding and while racing my buddy and while passing him(More Excitement) It hit again and it was all I could do to stay on the bike. Went to the hospital and they did cat scans mri ,mra tests and have found nothing wrong w/my head .So my ? is could this be coming from my topomax??