Patient: I have create a black and blue mark in the middle of my back from scratching. If my back sweats it itches when water is on it it itches. when I run or swim it itches. Just sitting around it starts itching. but the severity of this only occurs between Noverber and say february or March, and then stops. can this be relatedd to a virus? or bone fragments?The mark or black and blue never really disappears.