The first thing I would suspect is coccidia. Do you have any Corid? You can get the powder at TSC [it's labeled for cows] and mix 1/2 tsp per gallon of water. Make sure they have only the treated water to drink for 7 days. I'd probably also want to offer all of them plain yogurt, to help maintain good gut bacteria. The one that's acting off probably needs some extra intervention; I would keep her in a warm area, feed her scrambled eggs and make sure she's drinking Corid water.
The ones that have pasty butt need a soak to clean up that area or other problems can happen. When I have to do that for any of mine in the non-summer time, I do it in the house and keep the bird in a small dog crate with clean pine shavings in it, in a warm room, to dry; some people use a blow dryer to dry off the bird. I've not been that brave yet. LOL