Hi Robin - Interesting. i appreciate the detailed description. i'm fairly sure this is not a head injury issue, and i'm not seeing seizure activity. It's more like a tick. i've seen it happen when he has his head upright, and also when he bends down to eat or drink. He just takes a moment for the movement to stop and then resumes his activity. He looks healthy and happy otherwise. He participates in the hopping, flapping, chest-bunting types of skirmishes normal baby chicks do. When he and his two friends were out in the pen with the others, he held his own in the pecking order. i'll just have to keep an eye on him and make sure no other symptoms arise.
. . . and, thanks pricem11, but i liked your first, longer post better.