I had that wicked sore throat too. Day after Christmas. Then mucus mucus and more mucus. Didn’t test, but I am betting it is covid. And it is hanging on for so long! Sheesh. Hope you feel better soon!
here is something that really helped me.
I took warm salt water with two slices of lemon and spent a lot of time gargling and holding it in the back of my throat with my head tilted for as long as I could stand. I had to do this sometimes in the shower because my gag reflex sometimes would projectile it out.
I spent one day focusing on this and it really helped.
I am still battling the coughing. Mucinex fast max does help with that at night