I have two boer/kiko cross does approximately 5 months old. I've had them since they were 3 weeks old. They are both up to date on cd&t and worming. Both seem to be in excellent health and very active with no signs of anything being wrong. We feed them alfalfa and local grass hay, also a cup of grain to each in the morning and the evening. For about 6-8 weeks now one of them has been doing a weird head/neck roll. She starts at one side with her head, rolls it around, touches her back with her head, then finishes the roll on the opposite side she started on. She only seems to do this when she is bored, wandering the pen, wants out, etc. When she eats and grazes she is usually fine. She walks in a straight line fine, jumps, runs, and plays fine also. Any suggestions on what this might be? I have read about goat polio and though the signs are somewhat similar, I think I have ruled that out. A local vet told me it may be some sort of infection, or also could be a thiamine deficiency. Let me know what you guys think. Open to all opinions and further questions. Thanks. Also have a short video if anyone wants to see. I can email it.