My period ended on the 19th me and my man had sex on the 18 and 19. My fertile window starts on the…

My period ended on the 19th me and my man had sex on the 18 and 19. My fertile window starts on the 23 till the 28th. And I have a urinary tract infection that I haven't went to the doctor yet. But I woke up and I am spotting and it's brown.. Can I still go to the doctor because I'll have to pee in a cup and stuff will my spotting effect that and why am I spotting any ideas?