M.B.
Stress can do crazy things to your body. I would call your doctor though. PMS and pregnancy can make your breast tender but its usually both of them. I have completely skipped periods before and had 2 in one month before. I dont think your pregnant. Plus when you are extremely stressed its hard to get pregnant. Do you have a lump? Not to freak you out but my mom had a lump in her breast that she had removed, it was non-cancerous but they said it could be caused by high amounts of caffeine and stress. I would see your doctor if it continues.