Hello. I found this large, raised scab thing on my chicken's neck, to the left of the crop that goes near the wing and breast. It is about 2"x1" big. Her feathers pulled out super easy from it and you can see where they once were (little holes in the scab). She is not sensitive to me touching, poking, squishing it. She's acting ok otherwise, no limping, still eating/drinking, but a little lethargic in these normal activities. Any advice on what it is or how I should go about treating it. She is currently separated just in case. I checked her for lice and mites and none seen. All other chickens are fine.