ETA: UPDATE, she's fine. I've got a red star of undetermined age, probably closer to old then not. She's either is molting or is about too (lots of lost feathers) I'm not sure if she is one of the girls laying or not. (we got a big group of older chickens from a friend in the last few weeks). This morning she's quite listless, wasn't opening her eyes when I checked under her for eggs (she was in one of the nest boxes, but they sleep in there too). She's in my kitchen now, still being very quiet, not wanting food or water (for the last 10 minutes, I wouldn't consider that a symptom yet). I can feed a hard round mass in the back of her abdomen (a.k.a. an egg). My chicken anatomy isn't quite up to snuff, but I would guess it's just finished forming and is ready to be laid. Is it possible it's stuck? Or can you normally feel an egg that's ready to be laid? She is quite thin, so we'll just have to hope she warms up and feels better I guess. (FYI This is a production hen, I'm not taking her to the vet, but I will end her suffering if deemed necessary).