I have been having stomach cramps today and back pains all week? Please help 17 days ago I had sex with my partner but he pulled out before he ejaculated, he had just masturbated and ejaculated not long before, I was supposed to start my period the following week but I never did, then yesterday it started to sting slightly at the und of peeing. But today it wasn t as bad, and today I have started bleeding like a light period when my periods are usually heavy. I am worried about what it could be as I am usually very regular and heavy on my period. Also I have been having stomach cramps today and back pains all week? Please help? What could it be? Thanks