Hello, I have a hen and I've noticed this black scab on the side of her back. I just thought that it would heal over time but I just noticed that it has increased in size significantly and her skin has started to lift and peel back. The feathers around that area have been falling off. It smells as though she's rotting and I can't help but think that she's been attacked by something or maybe the roosters have been giving her abuse and it's just gotten infected. It is only the one scab. Is it a disease or is it a type of infection or something completely different? What do I have to do to clean it? Thank you so much.