My 17 week old Rhodie x Sussex is behaving strange. This was our most confident bird, she was first to venture outside when we first let them out of their house, and always came running up first for her corn in the afternoon. She is now not mixing with the rest and has puffed up her feathers, and is shaking her head fairly frequently. She eats layers pellets and mixed corn. We have seen her eating and drinking. We have checked her all over and cant see anything, no bubbles or froth around eyes or mouth, no injuries, no wheezing. Have not noticed anything strange with poo. Any advice would be greatly appreciated as we are new to chickens and would have to travel a distance to get to a vet.