Does your hen have any small spots on her comb? White or black? I'm almost thinking my hen might have Fowl Pox.
The description of the symptoms of this sound more sever then what I see on her but today I gave her a warm rub down with a cloth to clean up some of the food she had stuck to her, well as I was cleaning her up I noticed some dirty spots on her comb so I tried soaking it and getting it off of her. That wasn't happening because it's not gunk!
Im not to sure because when I looked at pictures of fowl pox some looked pretty bad but I also saw some that didn't look as bad.
I know she is dehydrated (working on that) which will keep her appetite down and her unsteady.
It's just a thought look over your hen for any spots
I also read that with good supportive care it will pass.