I've got a 10 month old pullet that has spent several nights outside in their run during this very, very cold weather we've been having lately. Even though she had access to a nice warm insulated house with her "sisters" she insisted on sleeping in the run (which has a solid roof). Anyhoo, I noticed today she keeps shaking her head and when I closed off part of the run and forced her into the house she immediately went into one of the nest boxes. She's not really hunched up but she looks like she just doesn't feel good. No sneezing or discharge. Since I rarely have sick chickens I can't remember what the head shaking means. Anybody know?