Yeah, it could very well be a bladder or kidney infection, or both. I would call your doc tomorrow morning to go in a get checked. You just have to pee in a cup and if there is certain bacteria in it they will give you antibiotics to clear the infection.
Or it could be another urinary problem. A friend of mine had her urethra collapse and wasn't able to go at all. She ended up full of poison and very, very ill because it took so long for them to figure out what was going on. So, don't wait, kidney infections that are let go are also very dangerous.

Hey, sorry for your troubles! To me, it sounds like a kidney infection because of the back pain. I tend to get a lot of bladder infections, which just cause cramping in the front, kinda like period cramps, and the doc always kinda hits my back on each side to check for pain in the kidneys. Like hotasfrick said, just go get checked out! No matter what it is, the sooner you get meds, the better. Til then, drinking cranberry juice and lots of water should help a little. Good luck!

Yep, as the ladies said. Kidney infection. Cranberry juice / cranberry extract, milk thistle, or alpha lipoic acid (ala) are all available at your local nutrition house and can help you out.