Precious Folks, This thick phlegm in the back of my throat lasted 2 years after COVID. I got choked on it at night. I also had a lot of mucus on my tongue in the a.m.. I scraped my tongue daily. I went to 5 doctors and they were perplexed as how to treat this.

What worked best was, cool mist humidifier, salt water rinses, elevate your head when sleeping, stay hydrated with water, keep your mouth extremely clean with extra flossing and mouthwash, NAC (Thorne Brand on Amazon)....I only took a half one), Lemon Ginger tea is a mucus thinner. If you want to thin out the mucus, Guafenesin (Amazon) helps. I did not take the Guafenesin with the NAC as they are two different things. Guafenesin is a mucus thinner and NAC is for inflammation and works more like an antihistamine to dry up the mucus. Vitamin C, D & Zinc as well. Also, Astelin spray (Prescription) works great
as an antihistamine.

I came to the conclusion (along with my Dermatologist) that COVID had attacked the mucosa and my salivary glands.

Yes, I have GERD, so we had to bump up my reflux med as COVID did a number on that too.

I empathize as this stuff can be miserable. Praying for all of you that are battling this.