NSFW: INFECTION? What is going on with my chicken??

I came back from a trip a few days ago (i had my friend take care of the birds), and today I noticed a small scab beneath my favorite chicken Rusty’s wing. So, i picked her up to look at it, and I happened to lift up her wing and THE ENTIRE area under her wing was scabbed/infected..

other details:

-Rusty is a chicken pretty low on the pecking order, so she currently lives with my small flock of turkeys.

-I have never seen any aggression between her and the turkeys (i have a camera on them, i was even checking them while i was away. i’m aware i can’t see everything that happens though)

-I already put her in a separate cage in a warm spot in the barn. We are already applying Hen Healer and disinfectants

-the other wing is totally fine

-My friend who took care of them never noticed any bleeding, and I didn’t either.

Thanks so much for the assistance with helping her! What do you think this could be? I’m totally at a dead end right now.