hi i had gone through your query and understand your concerns. i would come up with the possibility of BPPV;Benign Paroxysmal Positional Vertigo
may be the cause for her sufferings.
-medical history, physical examination, the results of vestibular and auditory (hearing) tests may confirm the diagnosis.
there is another possibility like ORTHOSTATIC HYPO TENSION;rising causes fall in blood pressure may produce similar vertigo.
I hope this is helpful for you, thank you