I have an 18 month old RIR who has been very healthy and active. She stays in a pen most of the time with her 5 sisters. I do allow them out to roam freely in my large yard on my days off. After I was gone for three days I came home to find her sisters roosting (it was after dark) and her lying on her side in the bottom of the coop on the ground. I checked with the family and they said she was fine that morning and had been pecking at a large cabbage I had left hanging during my absence. This was 7 days ago. Her sisters all seem fine at this point.
Once I found her I immediately took her inside to my master bathroom and put her in a crate, she was cold and I warmed the room and kept the lights off for the next 24 hours. She can stand and walk around, her eyes are closed much of the time, I started giving her combo probiotics and electrolyte fluids as my work schedule permitted. I genuinely did not expect her to make it through the first night. I have checked her for mites (coop is treated with DE routinely), her head is drawn back into her body making her crop (?) appear to protrude. Her comb is listing to the left dramatically. She will not drink on her own, but I can get her to take fluids with a syringe. About day five (still stunned she was alive) I added some corn syrup to the fluids she was being given. She is taking between 20 and 50ml of water by mouth daily and nothing else. Her recent eggs had been very thin shelled and misshapen somewhat but she had laid on the day I found her. For the first 72 hours her poops were very thin with green and white. Since that time they are more formed and brown and white. I have checked her vent and it is clear even her fluffy butt has very little poop on it. No sign of worms in her poops but the smell of the poops is wretched. Today I thinned some yogurt with the fluid solution and gave her 5ml which she took without a problem. I do not have access to a vet that treats chickens but have a medical background and want to do whatever is necessary to give her the best care. She was vaccinated for Mareks disease and obtained from a very reputable breeder as were her "sisters". Today I did notice that while I am feeding her she opens her eyes and looks at me which she has not done up until now.
Normally her diet consists of layer pellets, layer crumbles and scratch grains along with vegetable scraps and my recently the peppers in my garden. Any advice would be greatly appreciated