The other morning I went out to feed my chickens, and i noticed that one was still in the coop. I went in and found one of our gold sex-links sitting in a very rigid straight up position, she was almost sitting like a dog or cat. Her comb was very purple and was floppy. I removed her from the coop and brought her into the house in front of a heater, (we live in Colorado, and its winter so it is very cold, so I thought maybe she would get better if she was warm). She seemed to be suffering, she couldn't hold her head up, it was laying very limply next to her. She looked dead. She was there for a few hours at least, and pooped, (very runny, green) and she was not moving at all. I researched everything about her condition, but no results came up. We finally just put her out of her misery, it was clear she would not improve at all. All the other chickens are fine, none of the other ones are showing any symptoms of illness. Has anybody ever seen anything similar to this, we are new chicken owners so we are still learning, or known anyone this has happened to? I want to have a healthy flock, and hopefully prevent this from happening again! Thanks!!