Could be a combination of things. She may be going into a moult, but not seeing her, it is difficult to tell. A moult is very draining on a bird's system, and if it follows a month of broodiness, where she may not have been eating and drinking enough, it could be very difficult to handle. It's also possible that if she came off being broody, and her body wanted to start laying, but also wanted to moult, that could be very difficult to handle, as well. Does she sit in the nest box, or seem to strain? I would watch her for signs of egg-binding (an egg getting stuck), as well. Most birds will not lay if going through a moult, but her body could be generating mixed signals due to the broodiness and feather loss.
Will she eat and drink? Are you giving her lots of extra protein? What are her stools like? Has she experienced weight loss?
I would mash up some boiled egg for her, and see if she will eat that. Put ACV in her water, and see if that helps her. During a moult, I give lots of black oil sunflower seeds and mashed up scrambled eggs with plain lowfat yogurt on top.
I have been assuming that the feather loss was due to moult, but sometimes birds will lose feathers as their health spirals downward, as well, so keep a close eye on her.
You're doing a good thing, bringing her indoors, and keeping her warm. Sometimes darkness helps as well as it slows down the egg-laying cycle, supposedly. If it does seem to be a stuck egg, some people have had luck with a soak in a tub of warm water, too. It didn't work for my bird, but others have had it work.
Good luck with your bird.
