Randomly every month or so I'll have a minute of a very intense sensation all over my body that is very, very itchy. It happens mostly when I feel hot and damp, either from exercise or in the the shower. The first time it happened was when I was about 15 (4 years ago) and in a karate class, so I was again doing exercise. My body becomes more red than usual so I would assume the increased blood supply under my skin has something to do with it, but I'm not sure. Any comments on this would be appreciated.