Do you have pain with urination? Is the back pain more in your kidney area? It sounds like your doc was thinking kidney stone.
Blood in the urine can present in one of two ways: gross hematuria (blood that you can see in the urine), and microscopic hematuria (blood that is only seen when the urine is examined under a microscope). In your case since you are having lower abdominal pain also, kidney stones need to be ruled out by menas of an ultrasound.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.