Hen update:
I removed the lesions multiple days in a row and they kept regrowing overnight.
I took a sample from two hens and viewed each under our microscope (all three magnifications) and found nothing that moved on its own (no flagellated protozoa), but I did see bubbles (in the tissue, not only in the spit), so I do believe it was a yeast.
(The results from the lab/vet in January said the same. Inconclusive, but they believed it was a type of yeast.)
I don't know why it didn't respond to antifungals, but it did get worse on antibiotics/anti protozoan meds. Their breathing was audible this morning and I know we made the right decision...
With heavy hearts, we culled these hens today. We cuddled them and thanked them one last time and then put them down.
Chick update:
They had steadily gained weight after their meds for cocci & respiratory issues... until Wednesday when I saw a decline in the rate of weight gain/weight loss across the board. I then remembered seeing posts about repeating the Corid two weeks after the initial treatment! Tuesday marked the 2 week mark since I did the 5 day run beginning on Aug 25th! I wish I would have remembered that before they lost weight for a day, but they all seemed to be gaining steadily again today except for my little Jersey Giant. I think I will give her a drop of undiluted Corid twice tomorrow and the next day since her weight has only increased by 60%, whereas all the other chicks' weights have increased 100-286% since Aug 19th. My current plan is 3 more days of Corid, then the preventative dose (0.5 t/gallon) for another 2 weeks. They will be outside full time by then. (I let them stay a bit outside now, but they sleep inside still since they aren't fully feathered yet and are under 6 weeks old.)
Does anyone know if I can give them Nutri-Drench drops in their mouths while on Corid? What about yogurt? I only gave them two days of vitamins/electrolytes/probiotics (Rooster Booster) in their water after the first Corid five day run followed by a 5 day run of antibiotics. The Nutri-Drench does have thiamine in it. Maybe I'll continue the last 3 days of the 5 day treatment dosage (2 t/gallon) without anything else except chick crumble and then when I switch to the preventative dosage for another week or two, I'll add in vitamin drops to those who are still sneezing or not gaining weight as much as the others and give them all plain greek yogurt. (Currently, two are sneezing when they eat and another is not gaining much weight comparatively.)