I have an approximately 16 week old Buff Orpington (along with an Ameraucana and Buckeye) that I got in late June. Two weeks ago the little buff orp, who has always been on the sweet, shy, reserved side, just didn't look like she felt good. She sat perched a lot in the run, feathers puffed, just seemed listless. This was really her only symptom. Her poop looked/looks fine, she eats, although not as vigorously as the others, and she has no other external symptoms of illness/disease. I quarantined her for about 12 days, during which time the vet had me give her panacur to treat any potential worm issues, and I treated all the chickens' water with corid (for Coccidiosis). After that, I treated the water for 5 days with a vitamin/electrolyte supplement to replace vitamin B (per vet suggestion). She seemed to be acting slightly more normal. Two days ago, I returned her to the run/tractor thinking she might eat more if she were with the other chickens. But now I'm just not sure. She still appears listless. I see her eating and drinking, but she is very thin (breast bone protruding under her feathers). I described her the other day comparing her to a person with a heart defect or something. It's like she eats, drinks, free ranges (I let them out in the p.m.), but after a few minutes, she just has to rest and she will lay down for a bit, then get up and go eat, drink, etc. I'm at a loss at what to do. I've gotten sort of attached to her during her quarantined time. If anyone has ever had this experience and can offer some advice, I sure would appreciate it. I'm hoping she just needs more time to snap back (from whatever it is??). Thank you in advance for any help!