I have a hen who appears very unwell and need some advice. She seemed fine yesterday although she was sitting around more than usual. This morning, she didn't move off the roost. After a couple of hours, I moved her to a pen outside, separate from the others and she is just standing there. She is not very responsive and her eyes keep half closing. When I put water right next to her, she drank it and has pecked occasionally at grain but isn't really eating. I also put some grit right next to her and gave her some greens but she isn't interested. She produced some extremely watery diarrhoea. She is about 3 years old and has no signs of trauma. Her feet do seem to be darkish in color and she has a dark spot on one of her toes but I'm not sure how this compares to usual. The coop has pine shavings as bedding. She also has access to an outdoor run. I added some gatorade to her water. What else can I do? What is this? HELP!!!