TweetFWIW, I would suggest going to a doctor, OP. I'm definitely one who tries to solve things on my own, but if you're getting a lump developing, it could be related to estrogen, prolactin, or even some other imbalance.
I have a tiny tumor on my pituitary (microadenoma/prolactinoma) and it's caused several hormones to be out of wack and I actually have an Rx for caber.
Point is, if you have a problem, best bet is to figure out what it is rather than guess and guess wrong.
Best of luck.
Tweeti agree caber and femara may work but sounds like the issue might be beyond these