I have a chronic rash (I guess) on my posterior. It doesn't itch, but is red and sort of looks like small pimples. My skin, other than this, is really quite good and not prone to breakouts. Also, I don't recall having this problem until I was well into my 20's or maybe even 30's. Although it doesn't really seem like pimples, it does get worse and more raised shortly before my menstrual period. Now that I don't work outside the home, so no longer wear pantyhose, I thought it might improve, but regardless of what I wear it doesn't. This is really ugly. What can I do to improve it? What is it caused from? Thanks.