What causes blood in urine (my urine is dark) and I don't know what's going on and neither do my doctors. I have no flank pain or back pain (sometimes a minor pain in right side). Doctor said from test they ran on wednesday,,everything looks good (blood count, etc) and from what he can see there's no sign of an infection. That is what worries me because I am bleeding with no infection. Please enlighten on what this could possibly be.