Balding and breaking feathers

[Freckledfox23]

Hi there, this is my only hen with this problem. She has been loosing feathers for about 8months now and she had a period of regrow but it didn’t last long. It is not lice, she has no sacks on her or white things. I thought it might be mites, so we have done multiple treatments of permethrin dips, a flea and tick dip bath, the purple anti-canibul cream treatment and elector psp dip. Nothing works, she is still losing her feathers. Again she is the only one in my flock out of 15 hens. I have all hens, no roosters. We live in NM so we use sand as our coop floor, we have treated that with permethrin and DE. I’m at such a loss on what to do. She still lays, she eats normal, drinks, acts completely normal she just looks in my opinion awful and gross. Pictures attached

 

[nuthatched]

What ate you feeding? How big of space do they have?

 

[Freckledfox23]

What ate you feeding? How big of space do they have?

They have a run that is about 10ft by 18ft and we often open that up so they can free range in the backyard.
I feed them fermented feed. During the summer we use Tractor supplies producers pride layer pellets mixed with nature wise scratch texture feed, which I also mix in dried herbs -rosemary, pepper flakes, oregano and thyme. In the winter we switch to no fermentation and use kalmback henhouse reserve since it has higher protein, still with the added herbs. They are also fed mealworms 2-3 times a week and have access to oyster shells/grit year round.