Help with missing feathers

I have 5 red hens, we recently had a change of home and yard. During the lead up their move they were kept in their old run full time, they’re used to some backyard range time most days, so when the first hen developed a bald spot on her back and at first I thought thought it was molting, then I figured it was some boredom/bullying from the others. But the second hen lost some feathers in the same spot just after the move. I sprayed for mites and bugs in their coop, and sprayed them with mite repellent but it doesn’t seem like their feathers are growing back. Any ideas what it might be? The other 3 are fine, no bald spots, but some missing tail feathers (they lost their head hen to a fox last year and I think they were trying to figure out their order).