I would guess that she is either getting sick or isolating herself from the others, but with her grey comb, it sounds more like illness. I have a hen who recently resumed laying, and she has tsken to wanting to sleep in the nest box at night. It worries me with temps close to zero now, and I have lost several older hens lately who just became sluggish and separated themselves, then died within 2-3 days. They were all 5-6 years old.
I would try to get her drinking water, and offer her some wet chicken feed, chopped egg, tuna, or liver. If she is not laying, and her crop feels normal, she could have a reproductive disorder, such as internal laying or egg yolk peritonitis. Hopefully, she will get better, but it seems that cold weather this time of year can push some hens over the age.
I would try to get her drinking water, and offer her some wet chicken feed, chopped egg, tuna, or liver. If she is not laying, and her crop feels normal, she could have a reproductive disorder, such as internal laying or egg yolk peritonitis. Hopefully, she will get better, but it seems that cold weather this time of year can push some hens over the age.


