Cervical Mucus... Maybe?

Anytime I masturbate (which I don’t often) and I pee afterward, there is always this thick reddish/brown clump of mucus or something that comes out. It seems like it would be some sort of mucus plug because it’s normally covered with clear/white mucus. Any ideas what it is? I’m also super irregular with my period. It comes when it wants with the longest time being a year. My doctor said my uterus looks fine btw. I’m curious about the discharge tho.