Pain.. HELP!

I had sex on the 21st, and according to Glow, I was at 7.8% risk of getting pregnant. I'm not supposed to start for another week, but my boobs are seriously in the most pain they've ever been in. They're swollen, too. I've tried everything to soothe the pain and nothing works. My lower back is also hurting really bad, too. Any tips on how to soother breast pain and the cause? I'll literally try anything at this point.