Here, try this. Bring her in for awhile, so you know she is warm and unstressed by the rest of the flock. Put her in a room you do not use very often, and use a lamp for the lighting(if room has windows, close the blinds).
Buy a timer for the lamp, usually you can get these at
Wal-mart, they go into the outlet and the you plug the lamp into the timer. Leave the lamp in the on setting, and the timer will cut the power supply on and off as the timer is set.
You want to set the timer to mimic winter hours. You want to create "short" days artificially in this room. If it is the start of the internal laying, the "short winter" days should slow down maybe even stop production.
Pamper her for awhile. Feed her chick starter and other sources of good protein. Keep her well supplied with crushed up egg-shells(sometimes they prefer egg-shell over oyster shell) and her grit. I would also put her on a small dose of antibiotic in her water.
I would do this for a few weeks and then slowly change the timer settings until she begins production again. Hopefully, things would be back to normal and you can slowly(!) put her back where she belongs.
I know this may disagree with other people's advice, I'm not trying to argue with other people's advice. This is just what I, personally, would do in the circumstance.
I hope she improves, keep us posted! Maybe a few pictures of the vent area, both clean and dirty, would be helpful. If it does have a rash, try to get it in the pictures.
-Kim
