Yesterday I noticed one of my chickens seemed a bit off, she wasn't interested in food and didn't move a lot. Today she is worse, she just stands in one spot with her eyes closed and tail down. She isn't interested in food or water but when she went to the toilet her feaces were runny, off white and very smelly. Her comb seems a different colour too with the tips a darker colour: She is also just letting me stroke her which she never does. Any ideas?