Sorry this is not an introduction but an urgent request for help: For the last couple of days I have noticed that one of my chickens has gone off her food and has buffed her feathers out. She is still drinking, however today I have noticed that she is opening her beak frequently and shaking her head. There is no discharge evident, but I can see something yellow in her throat and there is a horrible smell coming from there. I am not sure if this could be a fungal infection, something stuck in her throat or possibly something more fatal. My girls are cooped at night and free range during the day. I would be very grateful if someone could offer me some advice on how to help her. Thank you in advance.