After rereading this in the morning/afternoon and not late night I realized my mistake. BPPV is normally the posterior, more infrequently the anterior, and to be true up/down vertigo only it would have to be both canals at the same time. The vestibular organ is odd. Either way, this whole scenario doesn’t even sound like bppv (peripheral) and is most likely something up line in the brain (central).
Read the book! It was so good as well. Not entirely the same as the movie. The movie was more of the premise with book plus some exerpts, but still amazing in its own way. I really enjoy both. Really easy read because of how it is written, and so much fun as well.