My younger sister, who is 14, somewhat frequently will drop to her knees, groan and clutch her head, and is completely unresponsive. It seems to go in batches. She had three a day for five days, two a day for ten days, etc. She only gets a week break between these bursts. Yesterday was the first of this batch, and once she stood up, I asked her what it was like, and she said this: "similar to fainting, except I still sorta hear what's going on around me. Everything is intense.