I often get pimple like bumps on my breast that stay about as long as a regular pimple does and never really look infected, I have had this checked out by my doctor and she says it is just from sweat and friction of the bottom of my breasts rubbing against my other skin. However, recently I got one and now it looks kind of black and not at all like a pimple, it has been there well over a month and I am getting kind of concerned. Has anybody ever had this before? Should I be concerned?