Will she eat and drink when you bring food to her? I had a similar thing happen to two hens. Both made it. I brought them inside - even with the dogs and kids - one of the bathrooms was a hospital for a a couple days. Long story short, after some electrolytes and yogurt they really bounced back. I'm not 100% sure but we feel like the Alpha hen was keeping some of the others from eating and drinking. Once they get a little dehydrated they seem to go down hill fast.