Ya know - I was thinking about Penny last night, and how you said you give corn syrup or honey and then she is okay. That sounds so much like a blood sugar issue. Maybe she's not a full blown diabetic, but crashes occasionally for some reason?? I used to have to give my Lhasa corn syrup when she crashed. She didn't have a head bob - she would just walk in a tight circle and be really disoriented. It was next to impossible to keep her stable even on insulin. She proved very difficult to regulate.
Just thought I'd share that with you - just one more idea to add to the confusion.