Did he perform a urine test? He was supposed to. That's the correct way to determine if you have a UTI. I wouldnot keep taking antibiotics if you donot have symptoms of a UTI. I think it is common to see blood in urine during your period. It is very likely that the source of blood is not your urine but your period blood has contaminated your urine. Think about the proximity of your urethra and your vagina!