Several months before I was diagnosed with bilateral breast cancer in Sept. 2015, I not only felt a swelling near the armpit of my left breast, but I kept smelling what I'd say was close to B.O. in that armpit. I shower every day, but couldn't get rid of that smell. After breast surgery which disclosed different cancers n each breast, the old sweat smell stopped. The right breast which had estrogen related cancer didn't produce this smell. I'd mentioned this peculiar condition to my primary care doctor before my mammogram, but he didn't seem concerned. However, I knew it indicated that something was up and I'm glad I trusted my own instincts and made the mammogram appointment. My advice: Trust your instincts. You know your body.