Im on the third week of my bc pills and last night i was diagnosed with a uti and given bactrim (sulfamethoxazole and trimethoprim). there was blood when i wiped. could it be the bactrim (sulfamethoxazole and trimethoprim)?

UTIs and Blood: It is not the bactrim (sulfamethoxazole and trimethoprim). It is very common for the inflammation caused by a UTI to bleed.

Unlikely: This is more likely to be vaginal bleeding rather than urinary, although both are possible. If you think seriously that this was from the urine you may want to tell your doctor about this. Some forms of cystitis produce bleeding, but it may need further follow-up. Hope you are better soon.