I have a red rash on the underside of my left breast. I noticed it last night when I was undressing. I don t think it s from my bra because it s only under the one breast. I thought it might be from sweating (I wear a U.S. SIZE 42D bra, so I tend to sweat under my breasts) but again, it s just the one (if I had a rash from sweating, wouldn t it be both?). I ve also been constipated the past few days and kinda stressed about that, and it s been freezing here (I m in New York City) so my skin s been dry & itchy in general. I just don t know if I have a serious medical problem or not.