Sick Chicken (not eating, lethargic)...what should I do?

[CooperMonkey]

We have a chicken who is usually the top chicken. Yesterday we noticed she wasn't joining the other chickens. Last night she didn't go into the coop at night and we had to find her and put her in ourselves. Today she is still not with the other chickens. We've tried feeding her scratch and is she is not interested. She basically just finds somewhere to sit and sits. She'll run away when we try to catch her. What should we do? Should we isolate her from the other chickens? Haven't been home all day so we don't know if she's drinking or eating, but I doubt it. Advice is appreciated! (She's probably 2 years old and one of our best layers. No eggs that we can tell, but it's hard to tell which eggs are who's).

 

[Donut Chickie]

I actually had the same problem except one of our other hens would constantly check on her and be with her. We took our hen to the vet and they gave us antibiotics for our hen and within two days she was back to her regular self. I do not remember what the illness was but I hope this helps.

 

[4Kids 8Chicks]

I am watching the exact same thing play out in our coop. I isolated our girl. She just stands or sits, barely seems there, and her comb is very light.

 

[CooperMonkey]

Well...her crop seems fine. Doesn't seem swollen or anything. Actually can't feel it at all. We just put her in a warm water bath and checked her vent. I don't feel an egg. (But...I'm not sure if I was doing that right???) We've isolated her and will check on her in the AM. She doesn't want to perch if that helps for any advice. My husband put her on the perch and when we checked on her later she was down. Advice?