She's very sick, but she's in good hands. Keep her warm but not hot. You can use a heating pad to give her warm comfort.
I have had a sick pullet for the past two months, and I clipped a heating pad onto the inside wall of her sleeping box for her to snuggle against at night if she craves extra heat. The last two nights it was ten below, and maybe 20F in her coop where her sleeping box is. She snuggled right up to the heating pad. I like it vertically so she can move away from it if she doesn't need it.