Dirty diva, chicken experts please chime in :(

Hi everyone! I will try to include as much info as possible given our current situation. I’ve had my chicken Copper for five years. Up until now the only causalities we’ve had with our backyard flock (started with 6, now have 3) has been due to a midday coyote attack. My dad was in the front yard and by the time he heard the commotion we had unfortunately lost 3 ladies. It was very devastating and we no longer allow them to roam unless a human is constantly surveying the backyard, in addition we now always blare loud music while they’re out on the town. Over the last 5 years they have been in great health up until now. We have never had roosters, just ladies in case that matters 💅

We provide grit with their feed, their main feed is Grubbly Farms fresh pecks layer feed (16% crumbles) oyster shells, cracked corn, and on occasion we feed them oats and grubbly farms mealworms as a treat. We keep their coop very clean. On Friday we noticed our friendliest lady, Miss Copper, had a poopy butt. My dad came to the conclusion that she had a yeast infection or vent gleet. We have added ACV to their water but their water is always fresh, I believe they have a well rounded diet, clean living quarters, and I’m not sure what they could be stressed about. We checked and cleaned the other 2 ladies on Friday as well, though their bottoms weren’t as poopy and their cloacas were not inflamed.

What we have done so far: cleaned and dried all 3 ladies on friday, added ACV to their water Today: cleaned Copper, cut a few feathers and applied monistat to her and the other 2 ladies. The other 2 ladies are far more skittish but we checked their behinds and wiped them, then applied monistat.

I attached a photo of Copper’s inflamed cloaca. I have been able to gently remove the poop/etc from her rear feathers and surrounding area, but there is a hard mass on her cloaca. We soak them in epsom salt for five minutes before cleaning to soften the area but even after doing so and using dawn soap to clean the area, the white mass is still very stuck. I am afraid if I try to force it off it will take flesh along with it.

My question is what are some changes we can make to cure this and prevent this from happening in the future? I read that you can give them unsweetened yogurt, if there’s anything else we can do please let me know. I think we should isolate her until it clears up but my dad is afraid it’ll stress her out. Our current plan is to continue cleaning, drying and applying monistat every day until it clears up? Is there anything other than ACV and unsweetened yogurt we can add to their diet? The ladies egg production and general demeanor has remained the same, they are always in good spirits and happy to see us. :(

Copper is not a happy camper in the last photo, that’s me drying her off. Any advice is greatly appreciated so my ladies can return to their fabulous usual selves.