Not sure I can save her, help?

[DellaMyDarling]

Very ill hen, my favorite lady
She has the most prolific infestation of northern Fowl Mites (more on this in a sec.)
We have been treating this girl for a doughy crop for three days now. I'm guessing her immune system was really compromised from mites, allowing for desirable condition to emerge for doughy crop. Usinga recipe from a BYC article that involves some kitchen seasonings and lemon juice, fed twice a day, crop massage for burps, etc. Does seem to provide relief and she's been a bit more spry until this afternoon.
Hen is now presenting with head down and back arched/tail low, or head pulled in and half squatting like.
She is 5yrs old and it's been a few months since last egg, but that could be normal for age? Her other same age hens have also stopped laying.
Hen has had a paler comb for a bit now, I attribute to the mites.
She is quite light, skinny. Has definitely lost weight in the past month.
This late afternoon, new symptom. Bulge under vent large enough to notice visually after her bath. It is NOT hard.

Still sweet and talkative to me, just oh so sad and clearly not well :'(

More on the mites:
Been treating hardcore for these evil creatures. She is the most impacted hen.
She's had TWO mite baths today alone. I've stepped up type, frequency, and dosage of Permethrin treatment.
These past two baths made a HUGE difference in mite population, but there are still creepers on her!

One of the new hens is really picking on her. Past two days I've seen her pecked, while already crouched, into a corner, and then hen stands over her triumphantly. I'm ok with this in a normal scenario, but the poor girl doesn't need that right now so I removed her from the coop.
Currently, poor Barb is in a crate of hay in the pantry. She has pellets and NutriDrench water available. She's still soaked from bath, I've tried rubbing with towel but makes her uncomfortable. She doesn't seem to want to sit, just crouches there. At least she enjoyed the bath!

I know you want poop pics. I'm waiting for her to produce.

Is she dying on me?

 

[RumneyRoost]

I wonder if she’s been laying internally? That could be the bulge, fluid in the abdomen.
Has her comb been plump and red since she stopped laying? Or did it shrink?

 

[DellaMyDarling]

I'd say that it's been fairly small and paler. I want to say June was the last time that any hens from the old group laid for sure, and I think she herself tapered off prior.

I wonder if she’s been laying internally? That could be the bulge, fluid in the abdomen.
Has her comb been plump and red since she stopped laying? Or did it shrink?

 

[DellaMyDarling]

Anyone?
She's really not well. Not sure what else to do for her

 

[Eggcessive]

It sounds like she probably has a reproductive disorder, such as internal laying, egg yolk peritonits, or even oviduct cancer. Most times we don’t know until a necropsy is done after death. Unfortunately, this is how a lot of hens end up after a few years. I would feed her what she will eat, and try to make her comfortable, while continuing to treat the mites. When she seems uncomfortable or suffering, then I would consider putting ner down.

Getting rid of the mites completely by treating every 7 days, and complete emptying and cleaning of the coop is needed. Then the coop should be treated as well. If the permethrin doesn’t help her, consider using Ivermectin Pour on 0.1 ml for every 2 pounds twice at 14 day intervals. Put it at the base if the neck along the backbone.

 

[DellaMyDarling]

Barb poop.

She then walked around house, clucked, now sitting napping again.

 

[RumneyRoost]

Given that she's older it's very possible she has a reproductive disorder, in which case palliative care is all you can do.

I would keep treating the mites as well, in the hopes that they've just knocked her on her butt for the time being.

Good luck! Make sure she stays hydrated.