this morning when I let my chickens out for the day I noticed one of the Cornish Cross females didn't run out and attack breakfast. When I went to check on her, she got up, ruffled her feathers and shivered, walked a few steps then laid down again. I took her outside and she again ruffled her feathers, shivered and laid down. She is eating the grass around her but will not move unless I urge her to. Her normal behavior is fairly active even though she is 10+ pounds. Her first poop of the day is mostly white with a tiny bit of green--not watery but not log-like either. The weather has been changing--going from 100+ degrees to the 70's and overcast within a few days. One of my other chickens, a Leghorn, was sitting for a day(no shivering) but is now up and running around. Do you think she caught a cold and should I separate her from the others? Or is she just old for a Cornish Cross? Thank you so much!