Hi there. We have a small flock of 2 Barred Rocks, 1 Cuckoo Maran, and 2 Araucanas. All chickens have been having some feather loss around the vent area, but the Barred Rocks have it really bad as well as some poopy butts and infection (please see photo - infected area is on the lower left of the bald patch). I believe this is due to recurring mite problems in our coop. I clean it out regularly (we have a litter system with PDZ where we scoop poop daily) and treat the chickens regularly with DE and sprinkle DE around the coop and on the perches. It's been really rainy lately so I've been trying an essential oil spray instead of the DE. Once a year in the spring I do a thorough clean and spray the coop down with permetherin to kill the mites. But the keep coming back and it's really bad this year. Maybe it's not mites but something else? It's weird that just the Barred Rocks are like this, although all chickens have some feather loss. Anyone have any ideas of what to do? I feel so bad for our chickens but also feel like I'm doing everything right!