Breast pain


So my breast pain is only when I touch them, when I'm not touching them they don't hurt at all. It has been hurting now for the past 5 days or so and I'm thinking about going to the doctors about it but I'm scared of two possibilities: pregnancy or cancer. I don't know if it could be pregnancy as I am on the combined pill and don't have sex but I do some other things with my boyfriend. Also my period isn't due for 9 days. And I can't feel any lumps in my breast for it to be breast cancer. Any Ideas what could be causing this? My main guess at the moment is that it could be my bras. I am D's but I sometimes have to wear C's because my others are in the wash. Also the wire might be effecting it. I tested something out the other day by sleeping without a bra on (which I dont usually do) and the next day they stopped hurting until that night when they started hurting again. Any ideas?