We have 4 ISA browns, just bought them about a week ago and they are around 9 weeks old. We have a great set-up, did everything the people we bought them from told us to and they have been with chickens for 17 years. Last night we noticed one of them was just sitting in one spot and not looking very well. The others were and are still fine. We put her in a box-seperated her from the others-and put some bedding, food and water in there with her. Her symptoms that we could see were shaking, breathing hard and fast, beak always open, not eating or drinking, barely moving, and can't stand. We thought we would lose her overnight, but she was still alive this morning. She now is only breathing what seems to be normally, but still cannot move or stand. She is always just sleeping and can barely even raise her head. Her poop is running white, and/or black. Can anyone please tell me what could be wrong, is there anything we can do for her or should we just put her down???? Could she have eaten something outside, or been bitten by something?? Please let me know!