Is it a tenderness that is constant or does it come and go? Is it sore to the touch? Does the soreness go away once you have your period? The soreness could be caused by the normal monthly changes in hormones. Continue to do monthly self breast exams. If you continue to be concerned or notice any changes in your breast, such as a lump or mass, experience soreness that does not go away once you have your period or notice a discharge, call your doctor.