I had something similar. At my annual checkup, my doctor noticed a lump in my breast and sent me for a mammogram. (This was about 6 months after I had stopped breastfeeding - which I had done for 18 months) The mammogram and ultrasound determined that it was not cancerous, that it was a cyst. They suggested I have it asperated. It had been awhile since I had stopped breastfeeding, but I started to recall how this was the same exact spot that had absolutely killed me when I had stopped. I had figured there was just a pocket of milk left that didn't drain. Anyway, I made the appointment to have it asperated, but of course on that day my daughter was incredibly sick and I had to cancel. By the time I got around to rescheduling, the lump disappeared - it had drained out on its own. (Granted, this was probably almost another year gone by at this point - life gets busy!) At my next physical, I asked the doctor to double-check. She said she no longer felt it, and it must have been from stopping breastfeeding. She said not to worry about it any more. That was about 4 years ago at this point. Good luck!