I saw my youngest of 4 hens scratching a lot and so I picked her up to inspect. Sure enough, she had what I identified as poultry lice. I sprayed her with some mite-and-lice bird spray, and added both DE and some Seven powder to their dusting area. I've been inspecting her weekly for the past month or so and I haven't seen any bugs since. But she still scratches! She's losing feathers around the base of her neck, and the skin in that area is very irritated: I do not have a rooster. My hens get along great and rarely peck at each other (usually only when fighting over treats). They all went through a soft molt last year (November/December), and this single hen is the only one showing these symptoms now. What's going on and what can I do to help her? Thanks!