I've Had Intense Pain Under The Nipple Area Last Night,

I've had intense pain under the nipple area last night, it's been over 12 hours and it's back again. Not constant but noticeable. I had a mammogram earlier in the year and it's all clear. What could this be? First time for this symptom. There was no intimacy leading up to getting the pain. I had the hysterectomy in July this year.