She has my sympathy - I've had that and it's the worst I've ever felt!
Please, look on youtube for something called the Epley maneuver and have someone help her do it. It's a series of movements you can do at home that can help slide the crystals back in place. A word of warning... she may be sick by doing this, but after I did it it reduced my dizziness by a lot.
Here's a good video explaining how:
https://youtu.be/CPLOd6vqWKI?t=38Another similar maneuver, if the first one didn't help:
https://youtu.be/mQR6b7CAiqkIf she doesn't already know which ear is the problem, have her figure out whether the dizziness gets worse when she lies down on her left or right side, whichever ear is down on the pillow is the culprit.
As I understand it, there are little crystals that float around in your inner ear, and however they settle helps your brain determine if you're looking left, hanging upside down, holding still, etc. Sometimes those crystals will get knocked out of place and send messages to your brain saying that you're spinning in circles even when you're sitting still. This can be caused by things like getting sick or getting hit on the head (that's what happened to me).
Plain old dramamine helped me a bit too during the several days it took to gradually feel normal again. I hope she feels better soon!!