I just got off my period february 27th. i had unprotected sex with my partner the 28th. i'm now spotting and having cramps. what's going on?

Spotting with sex: Sometimes intercourse can cause cramping and spotting, especially just before or after a period. Stimulation of the cervix by the penis causes the release of oxytocin which is the hormone that causes uterine contraction. The levels of this hormone are a lot higher during labor but lower levels still have some effect. This can lead to the cramping and spotting you are talking about.