@anon335508: Definitely have your mammogram and check-up, but try this also. Instead of using the eczema cream, try washing the affected area with a collodial oatmeal soap, like Aveeno, and then using something like Sea Breeze or even rubbing alcohol on it. It will probably burn like the dickens, but try it anyway.
I say this because it sounds like you could have what's called "interigo," which is a rash that occurs in skin folds. Often, it's caused by the candida fungus, so it's something like a yeast infection. The collodial oatmeal soap helps heal the skin, and the alcohol makes the environment not conducive to the stuff spreading.
Just try it for a couple of days and see if you notice any improvement. Good luck!