I am a middle aged woman, in general good health, and do not take any kind of medications except the occasional Ibuprofen. What I experience is: upon awakening, I feel this rush of pain that comes on like a hotflash in that it creeps up, very quickly, peaks within a few seconds then subsides and disappears with absolutely no after effects. I've had this experience since I was in my 20's and just recently learned my 80 year old dad experiences it as well. The pain is very hurtful, and the only way I can describe it is that it feels like every nerve ending in my body has been activated and flares. I can't say if it extends to my legs or feet, but I definitely get it throughout my torso and it extends to my arms, hands and fingers. A flush of heat accompanies it, similar to a hotflash. Any ideas? I have serached the internet and found nothing that describes this. I'm not alarmed by it, but mostly curious. What causes it? What is it?