[gemy]

I agree with the others. It is hard to understand at 9mths old why a 2+ lb Yorkie would mature to 5lbs, when at 8-9 mths old they have 80-85% of their adult weight. That would mean your pup should weigh in at 4lbs at 9months old to make 5 lbs at 1 1/2 yr old.

You are absolutely right to be concerned with the head movement you described, and I might not waste more time at that vets, but go to a vet hospital and see an internal medicine specialist.

Full blood work and BATS, also maybe an Xray of cervical and upper thoracic spine.

I do hope you can get to the bottom of this and your pup finds her way to health.