I've had lots of experience with vertigo - sometimes lasting for months. It's something to go to the doctor for. My first experience was sea sickness after not having sea sickness for my entire life. Eventually, I had vertigo constantly. Since I've dealt with it for years and seen different doctors for it and have had MRIs, I know what causes and works for mine. It took a very long time to figure out what worked best for me and this may not be what works best for her, but I'll share anyway.
Turns out, I have an allergy to dust and causes my sinuses to back up and dump fluid in my ears. I also have the crystals that the epley maneuver helps with. The epley maneuver does nothing for the fluid, though. If I do nothing, supposedly the fluid will dry out in approx. 8 weeks. The problem with that is that my sinuses are always dumping, so I need 8 weeks to dry out pretty much every day. My solution is to do a squirt of Flonase in each nostril every day and take half of a zyrtech every day. I can't take a full zyrtech because it makes me too tired. I used to use Bonine instead of the zyrtech and my ENT said that makes sense because the medications are cousins to each other.
There are times when I can months without using the zyrtech, but I've been on this current regimen for about 6 months. When I forget to take one of either allergy medicine, I start getting vertigo in about 2 days. If I get really bad positional vertigo (only happens when turning my head certain directions), I get the epley maneuver to move the crystals. Epley will help me with the positional vertigo, but if there's still mucous going into my inner ear (and usually there is because there's dust everywhere), I'll still have a general, albeit liveable vertigo.