Im on birth control. A week ago my period ended, for three days after that I spotted, I ussally only spot for like 1 day.
Yesterday me and my boyfriend and I had sex he came inside of me.
I started cramping later that night, my lower back started aching. Today it got worse my cramps in my stomach were so sharp I started to cry, then they moved to my lower back, also I always feel hungry, and empty even right after I eat. This has happened before but not as bad. What's going on? What should I do? Please contact me. [email removed]

It sounds like you might have a urinary tract infection. (with the back pain etc.) get treated asap