I found my hen like this today, she seems to be a target of my rooster. I have 15 hens. She has no mites, she’s one year old. I feed poulin as well as anything they want and I mean it lol No one else appears to have this.
That look like severe pecking. Either your rooster is really rough and should be removed or other hens are pecking at her. I would spend some time quietly observing your flock to see if you see anything.
I agree with @oldhenlikesdogs and i copied this from a BYC forum about using antibiotic ointment.
“Triple antibiotic ointment is used to prevent infection and promote healing in wounds. There are many posts on BYC that state that you should not use the ointment that has pain relief. However, other posts say that as long as the pain reliever in the ointment is NOT a “caine” type (like benzocaine or lidocaine), it is okay for use in chickens. Triple antibiotic ointment should be applied to a wound only after it has been cleaned.”
If you don’t feel comfortable using antibiotic ointment (which works well for me) then you can always use virgin coconut oil as it will help to keep the skin from getting dry and flakey