I've got about an 8 month old Rhode Island Red that Is tucking her head down to her chest and almost looks like she tries to lift it up but can't. It seems to be every morning and then again at night. My husband says when he checks on them 2 hours after feeding she is fine and you can't tell anything was ever wrong. She's still laying eggs but they have a white film around them and one was almost grey looking. Any ideas on what this is and how to treat? Everyone else seems fine.