Dying is not comfortable without people quality medical treatment and even then there's no guarantees. Have you talked to your parents about ending her misery yet? I'm sorry you are having to go through this, but she has had a long happy life. It seems like it is likely time to give her a...
If she was my girl, I'd let her go. Easiest, fastest, most humane ways to do so are decapitation, or direct shot to the head if you don't have a vet. Absolutely any vet will be able to put a chicken down and some will do it cheaply. Hang in there sweetie, I know you love her, but it doesn't...
When my wee hen had egg peritonitis, I knew it was time to put her down when her beak was open to breathe. She probably would have lasted a few more days, but I she was going, slowly, downhill. I chose not to make her suffer.
In my experience, sadly recent, hens with egg peritonitis drink like fiends but won't eat. If she's transitioning to the other way around, perhaps she's getting better if that's what's wrong with her.