I had this about 2 years ago. I had the blood tested & mammogram done. Everything test fine & no answer for why, just maybe put pressure on nipple while I slept.
Well in most cases people here are going tell you to see your Doctor... however you've done that and since he/she has ALREADY told you to take this medicine, then I would do so. I'd trust my Dr. more than I would these people. (no offense anyone)
I would imagine the reason for taking the tablet is as your Dr. said, to cure your problem. For further treatment, assuming the tablet doesn't help you, return to your DR and speak with him/her about it.