I had the fecal flotation done today. No evidence of parasites or worms. She was eating and drinking only when I held the food and water up to her mouth, and there was very little meat on her. She went from walking slowly two days ago to not being able to even take one step without falling froom lack of strength? I felt like by taking care of her, feeding her and making her drink (she was sleeping in my bedroom) I was just keeping her alive and prolonging her suffering. So I had the vet euthanize her. On the positive side I know now a chicken friendly vet locally who does a fecal test for very cheap ($16) and who will euthanize for free. That's good for me, because I just can't do it myself, and the only other chicken I have had die kept getting dug up by raccoons and that was out of my comfort zone to get up to a chicken carcass every morning.
Anyway, thanks for your help, I will be looking at poops more carefully from now on, and hopefully will catch these things early. Although it seems with EYP that there is not much you can do to save them if it happens.
Of course I am worried now, 2 of my other girls have not layed an egg in over a year and are about 2-3 years old. I believe my chickens have a healthy stress free life and they look and feel healthy. I hope that is the case.