What do these symptoms mean?

I have been urinating frequently. The left side of my back hurts, my lower stomach has been feeling weird, my pelvis has been having pains, I've been thirsty, I can't eat as much. I had sex but had my period 4 days after. It was very heavy and lasted the usual 4 days. Implantation bleeding doesn't last that long does it? It came at the normal time. I have been under a little bit of stress. This has gotten worse over the last month. My grandpa has diabetes & my uncle died from pelvic cancer a side effect of aids. Help! Sorry, it's a lot of info to read