How to tell if my flank pain is...?

I've been having flank and abdominal pain for months. Doctors cant figure out anything. It wouldn't be external/muscular pain, right? It doesn't really hurt much worse when I move. It burns to pee and sometimes I have bloody urine. My urologist doesn't think it's kidney related. I did have a blocked ureter, but it did clear up. I feel nauseous a lot of the time too and do throw up. I do get nauseous too when I havent ate in a while. I'm not sexually active, so no pregancy issues. What could it be? I'm in a lot of pain now and nothing helps.