Maybe look to a systemic infection that attacks the nervous system?
I was just reading about this over the weekend - weird things can happen:
http://www.peteducation.com/article....+2025&aid=3366
http://www.cvm.missouri.edu/neurolog...on/dyshome.htm
I think my boy has some weird, mild version of this...I found references to it near Montana too, and I'm sure that it's not isolated.
I hope it's not this....but I would be looking at combination antibiotics and other things.