Are you ruffling her feathers to get the permethrin dust to make contact? Just asking. When I dust my birds, I put the dust in a sock, then I methodically move feathers, tap the sock onto the bird to get a fine dust, rub it in and repeat.
I'm sorry you're struggling, parasites can be a nightmare.
Thank you. I finally heard back from the vet and she recommends using 1/2 mL of 1% ivermectin mixed in a quart spray bottle 2x a week.I don't think you have to worry too much if your main chicken house is not infested. Yes clean and burn the second house bedding. Glad she has recovered, thats always a food feeling.
Mites are devastating to babies, but the adults can take care and clean themselves. You may have to help her initially as she has been ill, but as she recovers she will hopefully start to bathe herself. You just need to make sure your chickens have adequate place to bathe.
The way I handle the babies infestation involves medicine and cleaning, because mites are a death sentence to the small ones. You can buy an anti-parasite medicine that says on the label "for use with internal and external parasites", for example i have a bottle of ivermectin that says this. So far you have done everything necessary to get rid of them. Just keep them out of the main house and away from the babies. Yes they crawl on your skin, but we humans can feel them itch and scratch them off, chickens have lots of places on their body they can't get them off if they get settled especially on the head and under wings, but if you dont see the red clusters then you caught them in time. Red clustsers are the infestations where they are sucking the blood and that is a pain the deal with. Only ever happens to my babies, never had problem with adults and i live in a parasite hell.