This evening the kids brought me one of our hens. She's a pullet from MM just now starting to lay. She was lethargic and breathing kind of heavy. I thought maybe she got overheated. I gave her some water and she wouldn't drink. About an hour later she was laying on her side, kicking her legs and her neck was extended all the way back to her back bone and stiff. Kind of like a seizure? Any idea what this could be? We have 30 other chickens and nobody else is sick...so far. They are in an enclosed pen for now but do run free range when the gardens allow. Any ideas are appreciated!