Had a few of those myself. They're enough to panic anyone- even the well prepared. I ended up being carted out of my office area (a secure area, I felt sorry for the crew that responded- they'll have to be checked out) and no one has been able to see them. They told me: a) Stress b) Alcohol c) Pseudofed d) Aspirin e) Caffeine f) Getting REALLY pissed at your coworker Now I only get them sporadically- once every 3 months or so, and usually under stress. Good luck... try and relax ;-) and keep getting checked until they tell you it's harmless and have it verily documented.