I also have had two situations in the last month where I went into the doctor to see if I had a kidney infection because I had visible blood in my urine. Both times I was given initial antibiotics and then the pain would start to go away and come back full force. The bleeding was so bad from my urethera that I actually passed what my doc said was mucus membrane. It hurts sometimes to urinate. The pain in my kidneys and the pain while urinating comes and goes. All tests came back with no sign of infection other than way too many white blood cells. Doc saw the blood in my urine, I'm not menstruating when this happens so the blood is definitely coming from my urethera or another part of that system. I'm scared. I don't see the doc again until Wednesday and I was told to see a nephrologist. Anyone have any ideas that aren't kidney cancer? I'm really freaking out.

Was an ultrasound done? It could be kidney stones.

They did an ultrasound. No stones visible.