Hello I am a 21 year old female and I've been experiencing an odd nasal mucus for 4-5 months now. I am a non-smoker, no one in my family smokes, and my boyfriend smokes tobacco occasionally, but he and I have been away for 2 months and I'm still having this problem. As you can see in the photo the mucus is mostly clear, but these black spots have been appearing both when I blow my nose and cough it out. It feels as though my mucus is thicker than usual and settling right above my soft palate. When I loosen this and able to cough it out (generally in the morning), it is very thick and brown in color. It's very odd I've never seen these black spots before. I have a history of sinus infections. Any idea on what's causing this?

This picture was taken tonight after getting out of the shower.