Why are become breast tender before 15days menses coming..,?

Estrogen: The estrogen level increases during the cycle until just before your period when it falls, then starts increasing again as you start the next cycle. By mid-cycle (the time frame that you note - 15 days before your period) your estrogen level is high enough to stimulate the breast tissue making the breasts tender. For many women a vitamin E supplement will decrease or stop that tenderness.