I have a buff Orpington who is 3yo. The last few days she just sits in the barn, doesn't go outside with the other chickens, eats VERY little. She moves around in the barn, but I usually find her in one of two spots where she is just sitting. She flew up on the perch (about 2 feet high) to go to bed, and couldn't seem to fly high enough to get up there. She did it eventually, but it took a few tries. I thought she was going to pass yesterday, but she keeps hanging on. The other chickens don't pick on her at all, just leave her alone. She also goes outside so I know she has enough grit. Any thoughts???