What Causes Pink Discharge,cramps And Back Pain After Having Unsafe Sex?

Hello my period started on the 7th of this month it normally comes on the 8th, and lasts about three days all of my life and I am now 31. This time it lasted a whole 7 days and two days later I noticed lite pink thick discharge as I wiped after using the restroom. It has happened three times since, and I have been having very lite cramps, back aches, hot flashes and have been very tired and sleeping a lot lately. I had unprotected sex with my fiance on the 4th of this month but I have never experienced anything like this before.