one of my chickens behaving normal during the day. When night time comes inside it's coop it starts making "scratching movements on its chest area. It'd walk backwards doing this until it topples over backwards. I took it out just now and there was no resistance at all, I could lay it on its side, checked the wings and between its feathers and couldn't see any reason why it'd scratch itself non stop. When I'd put it on the floor instead of being all defensive it would do that scratching again. It isn't strong at all. Is it time to let it go?