I have had pain behind my right breast for about three years.  I have annual breast exams and mammograms that have not shown any issues with my breast.  The pain is not constant.  I dont feel it everyday or every week.  When it does begin to surface its fairly painful. I feel it most when I take a deep breathe or when i move such as reaching or bending. When I palpate the area to find a sore spot i find nothing.  Could this be in my rib cage? the spaces between my ribs or even lungs.
Hiwith normal mammogram you don't have to worry if the pain increases on breathing it more so looks like it is related to the rib sit could be due to Costco Chat Doctor. Take care