I have three eight-month-old chickens that we got from Dare 2 Dream at 7 or 8 weeks. Two of them are laying (we get 2-3 eggs a day). They are very vocal, alert, and social. I'm beginning to really worry about the third,

Rosie.

Rosie has yet to lay. She had a slight limp for a couple weeks, it came and went. The limp is gone, but spends most of her time "resting," i.e., sitting down. She isn't social with the other birds, and sleeps by herself on a lower roosting bar. She seems to be a bit smaller that the other two, although she eats, drinks, and poops normally. But she seems confused. When I am hand-feeding them treats (apples, strawberries, and leafy greens are their favorites), Rosie misses the food by a mile when she's trying to peck it, while the other two girls have laser-beam precision. She can most often be found sitting by herself, sometimes facing a wall or fence post. This behavior has gone on for awhile now.

Her comb and waddles are very pale, and very small (almost non existent), while both other chickens have large, fleshy, bright red combs. She also often has her tail feather sort of... droopy.

I have checked her for mites, foot and skin issues, being egg-bound... nothing. She doesn't seem to have any respiratory issues, rashes, or abrasions, and lacks symptoms of most diseases that I've read about. She eats, drinks, and poops normally.

Is she just depressed? Is it possible she's a bit delayed? Or are these signs of a disease that I haven't read about? Any insight and suggestions are GREATLY appreciated!