I was looking for answers about my mucus. All these sites are talking about mucus in the nose an sinus cavities. But that s not where my, thick, dark green mucus is coming from. When I get sick, I spend the next three weeks coughing the stuff up from deep in my chest. The first week is the worst. I cough so hard, I can make myself dizzy, and my face almost turns purple. But back to the question. What/where does the mucus in my chest come from, why is there, and how can I treat it without having to pee every half hour?