Two days ago, one of my chickens was found laying on the floor about 8 feet down from where she was roosting. She had trouble walking and I took her to the vet because I thought she might have some disease the others would catch. By the time I got her there, she looked dead but she wasn't. She was fine the day before and showed no signs of illness. The vet kept her for the day but was unable to determine what was wrong with her and sent me home with some antibiotics and told me if she died, I should have an atopsy done. When I got her home, I was putting some food in the cage when she busted out of it and took off running back to the other chickens. She acted totally normal and hungry. That was Saturday night. When she roosted that night, I took her off the roost and put her back in the cage thinking she might still be unstable. The next morning, I put her back with the rest of the chickens and she acted fine until this evening (Monday). I found her kind of staggering, holding her neck down as if she was having trouble lifting it. She looks just like she did on Saturday morning. I have put her back in the cage tonight and have given her some antibiotics but I have no clue what could cause this. Has anyone else seen anything like this?