I m 19 years old, and I have been on birth control for almost four years now. I know I m not pregnant, but my breasts are very tender. They are only tender on the outside and it doesn t matter if I have a bra on or not. These has been going on for about a week now. I shouldn t be getting my period for about another month, however, about 2 weeks ago I was on antibodics for bladder infection . Would that have anything to do with my breasts being so tender?