I've had some kind of undefined issue for about 5 years now (long before covid) where I will go to sleep breathing fine through both nose and mouth as appropriate, sleep with zero problems and no snoring recorded by noise monitors, then wake up with a sudden onslaught of mucus which seems to generate itself (upon consciousness) throughout the upper respiratory tract and rapidly. Various sleeping positions seem irrelevant to results.

I wake up breathing freely, regardless of position. If I stay still, I can get about an hour max of no concern breathing/existence. After that time, or if I sit up, I have between 3 and 15 minutes before mucus seems to accumulate in my nose, lungs, and throat simultaneously. It starts as a mild cough to clear the airway, which I always think will be the end of it because it's a "clearing" or "productive" cough with a little spittle and/or grating feeling. Then, about 3 seconds later, some kind of loop triggers, and I cough dryly and unproductively until it's time to inhale. This repeats sort of randomly for several rounds, never really obstructing breathing and producing no obvious mucus; after a cough, I can inhale and exhale freely through my nose and mouth both, and nothing stops a full inhale/exhale cycle.

After 3-6 of those cycles, mucus magically appears everywhere; the mouth I hale and exhale becomes ragged and wheezing, the nose inhale becomes nearly impossible, and the coughs produce globs of white mucus that must be spit out or swallowed.

Sometimes it all disappears after a few rounds of this, but that's maybe 1/50 chance. If this cycle goes on for more than 5 rounds, the esophagus starts chiming in saying hey maybe I can help, and the rest of it jumps in too. Now every cough becomes a prelude to a gag, which may or may not become more. If the gag causes any output in the form of vomit, it (the vomit) is strangely not acidic like bile, nor does it contain any fragments or traces of recently consumed food/liquid. The vomit is purely aerated mucus, and causes zero pain while going the wrong way through my system. This goes on until the mucus is all gone and I breathe fine in all ways for the rest of the day, with maybe a brief encore 12 hours or so later, but inconsistently. I have no idea what this is and neither do doctors I've seen.

I am 100% sure this is the wrong place to document this and irrelevant to the rest, but it struck my mind while reading this comment as a thing to write down fully for the first time, and I trust instinct in this regard. Maybe someone needed to hear/read it, or maybe I just needed to get it out properly, who knows!