What Causes Blocked Nose And Phlegm In Throat?

Hi, iv e been snorting ketamine for quite a few years. Recently wen i take just a tiny bit my nose blocks and this goop forms in my throat that i can t cough up. It comes out through my saliva glands as foam. Last time wen I lay down the goop moved around my face depending which way i lay. I also almost choked on it. Any idea what this is?