Spotting... strings?

So I haven't gotten my period in a long ass time. But no, I'm not pregnant. I do spot sometimes, but it's not just a little red spot in my panties. I notice like, strings of blood (??) in my panties? And sometimes when I'm in the shower and I pee, (I pee in the shower. Who doesn't? If you say you don't you're lying.) they come out and I see them. I notice they're not red like fresh blood, but they have that brownish color. What tbe hell is it?