On Friday I experienced a sudden, severe headache (felt like a vise encircling my head at temple level) followed by profuse sweating, nausea, being shaky and hard to breath. After half an hour, I settled down and went home. After vomiting at home and eventually taking Advil, the headache subsided but continued until the next day. The nausea lasted until Sunday. I suffer from migraines but this was nothing like a normal migraine....it felt like my head was going to explode. What could possibly be the cause for the extreme symptoms. Thank you for your help.