He's still hanging in there

I think he might actually be gaining weight, his poop is still good and his favorite pastimes are still mating his girlfriend, my legs, and being a bully to my 4 month old drake lol.
Still trying to figure out exactly how to treat him tho. Hopefully the oxine works. That video really helps - I've bought one of those portable face mask nebuilizers that will arrive tomorrow! I'll use a spray bottle in the meantime.
I have to monitor him 24/7 because of the choking, which makes it all the more hard to get the supplies together and really treat him, and i'm trying to make sure he gets plenty of rest where he's not being disturbed by me or other ducks as after he's had some sleep he seems better.
I had to stop syringing the silver down him after only a day or two because the choking got worse and it got scary putting anything down his throat, especially while i'm still trying to understand what's going on when he has these episodes. I'm still treating one other sick duck with the silver tho.
When he does choke or whatever is happening, its quite distressing, I don't ever know if I'm gonna be able to help him breathe in time. I have several techniques now from trial and error e.g. if hes starting to struggle but it's not an actual episode, then gently pushing his tail down and his chest up while he's standing on the floor. Similar to the stance of an Indian runner, I guess. I dont keep him in that position for more than seconds, it's just a quick correction.
But with a full blown episode I have to immediately grab him, hold him in the air chest up (runner stance) momentarily, hold his wings down or they hit me in the face while he's flailing around, and whether or not I put any (gentle) pressure to his underside with my hands while i'm holding him up (or slightly hug against the side of my body) will depend on how bad he is. Then I lay him in my lap and repeat the process however many times is needed. I can tell based on feeling him take some deep breaths and making rasping noises, both good signs.
Theres also a really weird noise of like trapped liquid or something during an episode, which isnt good, it means I need to keep repeating the process. The deep breaths/rasping appears to dislodge whatever must be blocking his airway, after I"ve done what's sorta like a heimlich maneuver. I'm starting to experiment with massaging his throat too. He's got too much tissue in his throat according to the vet, so maybe when he's sick it gets more swollen, and becomes easy to choke on food/muscus.
Sometimes he'll even start choking when he makes one of those normal muscovy
drake deep throated hiss/growl noises (not the typical excited hissing that drakes do, but one of their less frequent vocalizations, often reserved for making towards other drakes). It makes me think it's his throat that's the problem, but 2 of his buddies are sick with respiratory infections, so it seems likely he is too.
I've never heard of anyone else with a duck with this extra throat tissue and the vets were pretty stumped by it too (they thought it might grow...hopefully it hasn't). So it's like charting unknown territory in a way.