Quote: They can get it at any time. Most older birds fight it off on a daily basis quite well, but if for some reason she got a little stressed or run down, it can start to take over in the gut. Is her poop normal looking? It is something that I do if I have a chicken that is lethargic, standing around, puffed up. It's just where I start.
Her poops are scant firm blackish pieces with lots of urates and water.
I would start with Corid and if she doesn't look better in 24-36 hours, I would worm if you haven't already. Have you looked at the poop page? It has great info, and you can tell a lot about a chickens health from their poo. I will try to find it.
ETA-
http://chat.allotment.org/index.php?topic=17568.0