With a heartfelt thank you to Ellen for this: a brief explanation and exercise from an ENT that you can do to get those wandering inner ear particles back over to where they belong and away from where they make you dizzy. Hold this position, this, this, this, this, and done. Vertigo gone, or it might take a few tries. My neck muscles agree with her that one should wait fifteen minutes between.
She figured out the mechanics of the thing and how to address it. Easiest cure ever.