Thank you everyone for your thoughts on my hen. To answer Rancher's questions:
1. She is a white crested black polish
2. We got her from Nature Berry Farm near Canandaigua, NY
3. She is 24 weeks old
4. We switched to a layer feed a short while back. Before that, a starter chick feed. They also have oyster shell available now that we have some layers. They get treats once in a while but nothing recently.
5. No traumas that I know of
6. No changes to the coop
She has been inside all day and hasn't improved. Seems to be weaker. Of course since she isn't eating. Now she won't really drink either. I'm not sure she'll make it through the night. It obviously isn't worth a vet visit even if I could find one, but I'm just worried she may have something contagious that the rest of the flock has been exposed to. I'm also dealing with my 6 and 7 year-old who have never experienced a pet dying. And my husband is out of town. So it hasn't been a fun couple days around here!