Thoght I'd add a few things now that I remember them. Yes it is from the same stain as chicken pox. If you had them you are carrying the virus. What wakes the the thing up is another question. Although it maybe stress related, it seems to affect middle aged the most. But you can get it at anytime, and can hit in just about any spot. On my major flare ups I had what looked like 2 small spots on my side about an inch or so apart. As soon as my doc saw it he knew what it was. At the time he gave me percocet but that was like putting a band aid on a broken bone, yes vicodin seems to work best for the pain .