Why are my breasts sore without menstrual AND pregnancy reasons?

[KatherineJ]

Both my breasts would be exceedingly sore, like someone kicked you in the nuts. Sometimes one would hurt more than the other, and this occurs at least twice a month. I am on Yaz, and have never missed a pill nor been late for one. I've had my period last month and am waiting for next week's cycle. So, I'm not pregnant. I NEVER have breast soreness before, during, or after periods. I am not on any other hormonal pills at all. I detect no lumps, however, I'm not a medical professional. All this began two months ago out of the blue and has persisted on and off for several days each time, at least twice a month now. I've researched breast cancer, and breast cancer is reportedly not supposed to inflict pain at all. I have no family history, distant or near relatives, with breast cancer on both sides of the family. I'm 27, and having had children has already reduced my chances of having breast cancer, but still... this soreness is so strange and out of place and without reason that I needed to ask. My doctor is 30 miles away and I can't afford to go there this month at least. We have a free clinic in the local hospital, but do they screen for breast cancer and are they even any good at it? Can anyone come up with possible reasons why I have breast soreness?