it takes a lot out of them and she may well be coming into moult as well. watch she doesn't get bullied when you put her back. they sit for three weeks and then are (generally) in a small run being mum-you know what happens to us when we are bedridden for a bit
I was surprised at how much it took out of my first one. they brood, moult and all of a sudden its winter.
the chicks will be fine now and she'll no doubt be fine whatever you decide
she may well pick up when put onto growers-have they been on crumb?