Open Question: Why are my boobs so sore?

I noticed last week that my boobs were slightly tender. I thought maybe it was just how I slept or something, so I waited to see if it went away. It's been over a week now, and they are even more sore. My breasts usually get tender a week before I start my period. But, my period isn't due for another 2 weeks. (So, they are tender three weeks before my due period, because they started hurting