I suddenly, started two days ago, have breast tenderness in one breast. Wondered if this has anything to do with just ending 10 days of heavy antibiotic use for suspected diverticulitis (prescribed metronidazole and ciprofloxacin). During that 10 days, did not take my calcium plus Vit. D supplements nor did I eat my usual greek yogurt daily. I am 64, post-menopausal, but do take bio-identical hormone replacement: biestrogen topical cram and progesterone tablets daily.