This is because bras are unnatural contraptions and are better avoided. Recent research shows that bras actually cause sagging and may be responsible for some breast cancers. Therefore, it's best not to wear a bra at all unless you absolutely have to. Certainly, make sure you go braless for at least 12 hours a day to allow the lymph nodes to drain and the chest to expand normally.
I think its the kind of bras your wearing.you should really look into getting your self some different kinds of bras. I had a bra like that to ever time I put it on I was in pain in this bra.I say throw it away.it isn't worth it all the pain.a good bra is one your wearing and you don't even no you have it on. Those are the really good ones. It's hard sometimes to find to find a good bra. But the different is it's worth it there out there you just have to find them... Good luck.get red of that one...
May seem odd that you are getting answer from a man, but lots of females in family - majority of their opinion is that it doesn't fit right, ergo, wrong size.