Is there any hope in saving her? Please read (Warning: graphic close up of vent in 3rd pic)

*First and foremost: my one vet who would see her called in sick today and is unavailable for the next couple of weeks (had to reschedule my dog and cat as it is, ugh).* This is Rebocka, our 3yro Rhode Island Red. I noticed she was standing off by herself a few days ago and she’s seemed more and more isolated in the days since. When I picked her up yesterday (that she couldn’t get away from me is alarming in and of itself), I was horrified at how emaciated she was under her fluff—she is just skin and bones. :(

She is also very pale and anemic—I thought at first (last week or two) her pale comb just meant she wasn’t laying, but yesterday on top of everything else I was observing I realized *all* of her is pale.

Her eyes are clear, vent is clear, mouth is clear (though pale), and her feathers clean and in good condition. Her crop is small, hard (probably the grit inside?), and empty. What there is of her belly is soft with no sign of egg impaction. I can find absolutely zero signs of mites or similar parasites, and the rest of the flock is their healthy obnoxious selves. I’m starting to think she is in some sort of internal disease process I can’t undo, but I’m trying to do what I can in the feeble hope it will maybe make a difference.

She isn’t really eating or drinking. I swear not 4 days ago, she was greedily pecking treats out of my hand with her sister, but now she won’t really eat. I put her in chicken jail yesterday to keep her safe and under close watch and offered her scrambled egg; she ate one bite and nothing more. This morning, genuinely surprised she was still alive, I tried again with dried mealworms. I’d pry her beak open, place a mealworm just inside (NOT force feeding or shoving it far back—I know better than that), she’d finish positioning it and eat it, peck and eat a few more in her own, then stop. I offered water like I would a newly hatched baby—dipping her beak in it—and she’d have a liiiiiittle bit then stop, but would eat a little more after using the method above. I then made a slurry of warm water, one raw egg, cottage cheese, scratch feed, and quick oats, and while the rest of the flock lost their minds over it, poor Rebocka in her cage just ignored it.

Any ideas and/or hope, or is this just part of the sad reality of owning chickens?