Ah . . . My symptoms are very close to yours. One nostril is obstructed much of each day and night, and there is also intermittent runny nose, all in the absence of positive findings for any sinus infection or nasal polyps (so far). I have a 25-year history of severe dry and my obstructed nostril (and I don´t mean ¨obstruction¨ literally, since the jury is still out on whether there is any physical blockage or, rather, just impaired airflow) is on the same side as my much more severe dry eye. So my working theory is that whatever disorder produced dry eye in my late adult life (and itś not Sjogrenś, btw) also left me vulnerable to severe drying of my nose and sinuses -- and the severe dryness, post-COVID, has, in turn, damaged ciliary function on at least one side of the nose, slowing down both inspiratory and expiratory air flow. I have put myself on long-term dosing of Ivy Leaf (with Thyme) to improve ciliary function (and this can help in lower respiratory airways, too), without any clear result from that so far, and have now moved on to regular use of serrapeptase (chosen very reluctantly, since this was first discovered in and extracted from silkworms who would never consent to this exploitation of them, if given a voice). I am only in the very early days of trying serrapeptase (and other enzymes that I get from a product called MucoStop), but I believe that I may possibly be responding with some improvement to the serrapeptase. That said, I have also been following a thiamine/B1 repletion protocol all this time, with my doctorś approval, based on our observation that a multitude of other problems I have had since childhood are all often associated with either thiamine deficiency or a hereditary inability to absorb or store thiamine derived from diet. That protocol involves steady trial and error on best type and dose of thiamine for oneś particular needs, but since I have been pursuing this B1 protocol for a month or more, my possible very recent improvement may reflect some response to thiamine repletion. Your post, in any case, has reinforced my sense that those of us who have dry eye syndrome (and we know who we are, because we are NOT talking about the slightly annoying dryness/grittiness/burning that almost all humans sometimes experience, and are, instead, talking about what can be a seriously disabling and painful ocular surface disease) may bring to COVID some metabolic problem that opens us to risk for chronic sinonasal problems. This is NOT to say that we cannot recover, though. To do so, however, we probably have to reach long into our pasts to discover vulnerabilities that may explain why long COVID has manifested in us the particular way it has chosen. If you explore serrapeptase, please be sure to look into dose levels that have been both clinically tested, on the one hand, and anecdotally reported in the nootropic community, on the other, and please closely observe the rules for taking this enzyme on a truly empty stomach and seeking out a product that has been made acid-resistant. I will see my third ENT doctor next week, and if he detects anything newly enlightening, will try to report that here soon.