Edited by chicknmania - 1/8/16 at 5:22pm
If you can take her to the vet, certainly do that. In the meantime, try some Hypericum Perforatum. It won't hurt her, and might help. Directions for it's use, as well as the umpteen billion responses, are in a thread on here called St John's Wart. I've had good luck sometimes with Hypericum Perforatum.. You can get it at health food stores or vitamin shops, around $8.00 for a tube of 100 tabs. You want the 30C size.. Follow the directions carefully, if you can't find them let me know. But start it today if you can. The thing about it is, the sooner you can start treatment with it, the better.
Also, if she is not eating or drinking, and hasn't been, you should be tube feeding her. It is not difficult,, but I think it's a little stressful, mostly for the people, especially if you haven't done it before. If you want directions to do this, let me know, or Kathy (Castcartpony) has directions on her page, or she can help you directly. Lots of people on here can. It's worth a try, too.
Well, they won't all get it, though some might. You might not have any others get it. It's just the luck of the draw, I think. If you can get some Oxine (not the kind with crystals) mix with water in a spray bottle and spray everything, including misting the birds themselves, and you can put a few drops in their drinking water. You can do that with Oxine, but not bleach. Oxine is pretty pricey, but a little goes a long way, and it's awesome disinfectant. If you can't get it though, wash all the feeders and waterers with bleach/ water solution. And pray. If you do have another one start showing those symptoms, start them on Hypericum Perforatum, and I mean as soon as you see they look like they have the same symptoms. Either they will get it, or they won't, and chickens (even chicks)have remarkable immune systems, for the most part. So you might not have any more worries at all. It's not worth spending a lot time fretting over, imo. Sometimes just one bird will get something and then you never see any trace of it again in the flock...for months, years, or ever. .