Maybe you can save her if you get her some antibiotics. Mix them as directed and if she won't drink, then use a dropper to get them into her. Hope it works for you! I also hope you get some advice from someone other than me. I really don't have all that much experience.
When I found a hen like this and she died. I went out and found that my other hens were shaking their heads and I treated them. I also wanted to know why they were sick. I went in the coop and started digging around and found that we had a water leak over some hay. Hay molds quickly!!! There was a lot of mold and I am sure that is why they were sick. I pulled every bit of hay out of the coop and fixed the water leak. Once we got it all dried up in there and treated all the chickens, they were fine. Hay is not such a good thing in the coop. We stick to wood products now.