Hi,
Many women have breast tenderness and pain, also called mastalgia. It may come and go with monthly periods (cyclic) or may not follow any pattern (non cyclic).
Non cyclic pain is most common in women 30 to 50 years of age. It may occur in only one breast. It is often described as a sharp, stubbing pain that occurs in one area of a breast. Occasionally, non cyclic pain may be caused by a fibroadenoma, a cyst (both benign findings) or maybe an infection as you have stated.
You are more likely to have breast pain before menopause than after menopause and the pain can get worse with changes in your hormone levels or changes in the medicines you are perhaps taking.
Try to cut down on your caffeine intake and salt and see if it helps,until you see your doctor.
Breast pain is not a common symptom of breast cancer,but I would advise you to see your doctor or preferably a Breast Specialist for a clinical breast exam and also ask him about the hormone therapy that you are actually on.Estrogen pills have been known to put women at risk in developing breast cancer and you should really discuss with your doctor what other options are available.
Take care and best wishes...