Sore breasts

For the past 2 weeks my breasts/nipples have been very sore. Almost sore to the touch! I have been on birth control for 3 years and since starting it, I haven't had sore breasts. So this worries me a bit. My period is coming up in like a week, but again, since starting birth control this symptom hasn't happened.. Could it be an early pregnancy sign? I'm just hoping for some answers, or if this has happened to anyone else..