I have similar problems which affect me at night only, at least bad enough I can’t sleep. I have used the nasal rinse w/saline and a bit of Alkalol. I have also used a humidifier. Have not tried Mucinex, but that is my next step. ENT said I had a deviated septum that he could fix. I have had that all my life and my problem has only happened recently; Also, I have quit smoking I hope for the last time. This time it was a Christmas present in 2016.