I supposed to have my period on Jul, 30 but it didn't show. On Sunday Aug, 3 I had dark red spotting (size of a coin) and nothing for the rest of the day. Today I had the same during my bowel movement, and nothing for the rest of the day. I had sex on the day of my ovulation. I know this because I used OPK kit. My period is usually on time and never late. I experienced very mild cramping on and off from Jul, 29 to Aug, 1 which I thought my period was going to come but didn't. My boobs are still hurting until now (similar to my normal menstrual cycle). Is this something I should be concerned about?