I'm on CD18 of a 25-28 day cycle. I'm due to start my period on the 12th or 13th. Always regular. My husband and I had sex on CD9 and 11. We started without a condom but quickly went to one both times. Both times we had sex it was during my fertile week. Last night I had strong backaches and cramping, and then today my breasts are very sore and I've had brownish pink spotting! I've never ever had that happen before. Should I be worried or is this a new thing that my body is doing? Any advice would be very much welcome. Thanks!