Why am I still cramping 7 days after my period was over?

Weds I started my period on the 4th of May and ended May 7th, Well I started cramping again on Saturday the last day of my period. The cramps was small cramps nothing that bad, Then Sunday came around and I was still cramping so I went to walmart to take a pregnancy test and it came out to be Negative. On Sunday I also started to feel a little uncomfortable at my Vagina like I was about to get a UTI or a Bladder Infection I started peeing a lot more then Usual but I started peeing a lot more then Usual before I even started my period. Me and my boyfriend had unprotected sex on the last day of my period in April 17th and I took my birth Control pill right after. I'm a 28 day cycle, the pharmacist said that I couldn't be pregnant. I took 2 Cranberry Zaro pills and Im starting to feel a little better for the UTI or Bladder Infection but it still takes forever to pee. I also started lossing my appetite too, I still get growling and stuff like I'm hungry but when I eat I can't really tell if I'm hungry or if I am hungry. I'm still cramping. Please help me out I don't know what is going on.