Supposedly I've never had covid however a few months before we heard of covid I had a horrible cough headache just generally feeling nasty. I've never tested positive for covid however I've had for Moderna vaccines. Since that time I have suffered with the same exact issue thick clear mucus so thick I can't break it loose I can't blow it out my nose sometimes I can't even swallow it. I've tried everything as well doctor sent me for allergy tests I'm allergic to nothing they say had a sleep test for sleep apnea nothing there. I have it so bad sometimes I just stay up all night and get no sleep at all. I use as Azelastine spray twice a day along with a Saline spray. I also have a perforated septum due to a botched septoplasty to correct deviated septum. Going tomorrow to have a septal button placed over the perfection hoping this helps. My new ENT is performing the procedure. She sent me for a CAT scan of my sinuses and it shows various spots of thick mucus. I still believe it's from covid vaccines or possibly covid itself just went undiagnosed. Good luck you're not alone.