I had sex with a woman who was "spotting" a bit during sex, but we kept going. The condom broke but we continued afterward without it. Later that night, when I went to pee, some red stringy stuff came out and I thought it was just some of her "stuff" coming out of my dick after having been stuck there during intercourse. However, the problem arose again last night, and this morning there was 4-5 red stains in my underwear around where my penis' tip would have been overnight. How likely is this to be an STI or UTI, and if so, which one? How severe is this?