I've got it, too...My pre-Covid sinusitis got much worse after the virus: constant PND (clear mucus) down the back of my throat, sometimes down into my chest. I can breathe, but my lungs feel irritated, sometimes like there's an elephant sitting on my chest. I've been doing NeilMed 2x/day -- first with saline + budesonide + mupiricin, now doc switched me to saline + gentamicin + desoximetasone + drop of baby shampoo. Finished 5-day course of prednisone. Nada. On 6th day of amoxicillin and no change. Sometimes I have full body aches, leading my doc to wonder if the syndrome might be viral. I take Gaviscon Advance at night (have to order from UK via Amazon) in case there's a GERD factor. Staying hydrated, but...OMG, it's so much worse in the morning what with the congestion and gag coughing. I just feel exhausted and sick. Weirdly, sometimes by nighttime, say midnight, I feel pretty good. Don't know what to do next but may try acupuncture and then, at home, EFT (tapping). Couldn't hurt. : ))