I've had phlegm in my chest/throat for months
When I lay down, I notice phlegm in my sinuses down to my chest. Occasionally, I will cough some up but it more or less feels stagnant down there. I have it when I sit down too but it's more pronounced when I'm on my back. It's not colored so I don't have an infection. Also, I quit smoking about four months ago. I would say this started shortly after I quit. I was never a huge smoker. I smoked on average about two packs a week. I also smoked natural cigarettes.
I would go to a doctor but I am uninsured.