Spitting up bloody mucuos with black residue! What's wrong w

Just tonight I brushed my teeth and gargled with Listerine, when I spit out the Listerine there was a large amount of black/gray residue (so gross and in shock!). Then I proceeded to spit from the back of my throat and there is a good amount of blood. My throat isn't sore just feels like somethings in there. I have only smoked 2 cigarettes in my life so I know that's not an issue. I am making an appointment with a doctor tomorrow but was wondering if anyone knows what could cause this!?!? Please help me!