This morning I noticed that one of my 2 year old chickens wasn't pecking around like the other chickens, she was just laying there. I put her in the nesting boxes to see if she had to lay an egg, but she just jumped out and stayed on the perch. I tried to give her some yogurt ( her favorite food), but she wouldn't eat anything! She won't drink either! She's just standing there. She seemed fine yesterday! What could this be and how do I help her??