Pain is rarely a sign of breast cancer, but it can be. It's good you got it checked before, but if its been going on that long and you are noticing new symptoms I would definitely go back to your drs and ask to be checked again. From your post you will worry till it is checked, so if you have already been worrying a few weeks, I wouldn't wait any longer for it to sort by itself.
Assume you have done the obvious like check your bra isnt rubbing in that spot?
Since last year I have been experiencing pain in my breasts. It feels like stabbing pain and usually on the left side and under my arm. My GP referred me to the breast clinic for a ultrasound and it came back clear. I was told the pain is probably due to my breast sagging and maybe wearing the wrong bra. I wasnt convinced with the "sagging* bit as I am only 36 and have very small breasts and they are definately not sagging! Anyway as the scan came back clear I didnt think much of the pain even though I still have them on and off. However a few weeks ago I notice a small red mark on one of my breast. At first I thought it as a insect bite so didnt think much of it but now after looking at it more closely I dont think it is a bite as there is no dot in the middle where the insect bite would've pierced the skin. I hope this make sense, as usually in the past when I have been bitten, the bite has a tiny red dot in the middle. Also the red mark has become a bit scaly.
Should I be worried and have it checked out? I have become more paranoid and definately more aware over the past year since my mum was diagnose with BC last year.