My chickens have been cooped up several days because of bad weather. The last couple days when I went out to take care of them there is one hen that would sit right in front of the door, I'd have to push her out of the way to get in. Other than that she looked OK. This morning we went out there and she was dead, there was bright green poop stuck to her butt. What caused that? And what do I need to do for the other chickens? Should I get them out of the coop? Do I need to take all the litter out and bleach the coop?