I have a young hen (approximately 5-6 months old) who is quite ill. Several days ago she started not wanting to come out of the coop and stopped eating and drinking. A couple months ago we had a couple chicks die from coccidiosis (despite me treating with Corid) so I assumed it was that again. For the last 3 days I've had her inside and have been force-feeding her and giving her water treated with Sulmet. She has made no improvement and is very thin and miserable looking. I am realizing now, however, that she's not presenting the same way that the chicks did. They were also lethargic and not eating or drinking, but their tails were droopy. This hen is hunched up with her tail up and fanned out. None of our hens have started laying eggs yet, but I wondered about egg-binding and felt around her vent but don't feel any hard masses. I've tried Google to find out what else this could be. Any thoughts? I'm afraid she isn't going to last much longer.
Thanks in advance for any help.
Here is a picture:


Here is a picture: