Just read this... dunno if I am repeating...

Benign Paroxysmal Positional Vertigo Causes

The cause of BPPV is often a mystery and in about half of the occurrences of BPPV, the cause is never found. It is unclear why small particles (crystals) become dislodged within the inner ear. It may be due to minor head injury or because of repetitive head movement (for example; the up and down head movement that occurs when working in front of a computer screen or when cleaning or dusting above head level).

"the up and down head movement that occurs when working in front of a computer screen"

So that's why I am such a dizzy twit!