I have also experienced this same problem over last several years off and on. The first episode occured after I had laproscopic surgery with complications of a collapsed lung. When I was released from the hospital my left backside was very sensitive and could not be touched. It lasted about a week or so. Not long. The next time I experienced this was a couple years later on my upper check and forehead on just one side of the face. I asked my DR and she said it may be shingles. She was not concerned or very interested. This latest occurance is effecting my upper left thigh. It's very sensitive to the touch and feels like a sunburn or rash. But, hurts only when touched. It is not red at all. Sometimes it aches, but maybe that's just in my mind because I'm so aware of it. This started about the same time I noticed some bug bites or it could have been a reaction from a plant, I don't know. But, they are on the same leg on the inside of the thigh and I feel it's connected in some way.