Hen not eating, not walking much, liquid droppings...

[Kneedles]

Yesterday, while keeping a close watch on one of my other hens, which has been receiving prescription antibiotics and has almost recovered, I noticed that a different hen had suddenly become sick. She was hunched over, so I forced her to drink water treated with Aviverm (broad-spectrum de-wormer) and water treated with Stockman's Friend (a mixture of cider vinegar, garlic, seaweed, and honey). After this, she started standing up more, but she was preening a lot, was not walking much, and did not eat anything for the rest of the day apart from a tiny amount of raw egg. Still, she somehow made it to her regular roost that night (~50cm above the ground).
I have considered the possibility that there is something wrong with her crop. I forced her to drink the same treated water again today. I then tried to massage her crop, but I don't think that it feels 'doughy' or stiff, so I did not do this for long. During the treatment, she produced droppings twice; it was mostly a clear liquid both times. She still is not eating and is able to remain on her feet, but is not walking much.
The weather has been very cold and rainy recently; could this be related to her sudden illness?
Her feet and belly look normal. I don't think she is producing eggs currently.
She is almost five years old.

 

[azygous]

It can't hurt anything to oil up her works. Crop disorders are quite a common reason for a chicken to feel unwell.

You said the other hen was gaping and gurgling. Those are both common symptoms of impacted crop with possible yeast colonizing it from not being able to empty.

If you give her a couple spoonfuls of oil tonight, then check her first thing in the morning to see if the crop has changed in any way. Sometimes with impacted crop, you may smell a sour odor much like sauerkraut. That smell indicates yeast.

 

[azygous]

You do need to rule out a crop disorder. The way to do that is to check her crop first thing in the morning before she eats or drinks. If her crop has anything in it, she likely has a crop disorder. If you aren't sure about crop disorders and how to treat, this has the information to help. https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/

What has been ailing the hen you say has been treated with an antibiotic? Could this hen have come down with the same thing?

 

[Kneedles]

The hen receiving antibiotics was prescribed them on the basis that I twice saw her behave in a way that suggested a respiratory infection (she gaped once, and made a gurgling noise once), but I took her to the vet primarily because she was sitting down more often than usual. The vet said that she appeared to be perfectly healthy apart from some possible early bumblefoot that was promptly treated. This hen still sits down when she shouldn't, but she hasn't been gaping or gurgling since treatment started.
She was always eating well, though, and the hen that I am currently most concerned about has seemingly gone off food completely.
Should I try using paraffin liquid?

 

[Kneedles]

Update: Apparently I did something right, because yesterday afternoon she started moving and feeding normally again, and she was still better this morning (though I did see her sit down in an unusual place once, which is always cause for concern to me). I took her to the vet this afternoon. The vet said that she seemed healthy, but because she gaped a lot during the vet visit, the vet suggested that I should purchase some antibiotics for her (the same kind as the antibiotics that one of my other hens is currently taking), so I did.
This hen also gaped a lot during the trip to and from the vet. One of my other hens also did this a lot during a visit to a different vet for a completely different reason last year, but that vet did not comment on it. I think it is fair to conclude that gaping is just a stress response that my chickens exhibit; the hen has not gaped since I took her back home. I did not notice how much the cost of antibiotics contributed to the vet bill last time, and if I had, I think I would have rejected the idea of buying antibiotics for the hen in question.