It's called vertigo and yes, it can be totally debilitating. Ginger tea helps with the nausea and vomiting. Here is a small list of things that are supposed to help, but make me very sleepy. At times, it is the only thing that let me sleep, as just turning my head caused the world to spin and my head to ache.
Another possibility is Meniere's disease.
It may be helpful for her to see an audiologist (ear doctor) to check her ears, if she has not already done so. I hope by this time she is feeling much better.
Sounds like labyrinthitis. It is a deep inner ear infection that causes a ruckus with the inner ear fluids. She could be out of commission for 3-8 weeks if so, and might have some residual symptoms. Give her some benadryl maybe to see if it relieves any pressure, or at least helps her sleep. I agree that she should be taken to an audiologist, or an ENT (Ear nose throat). Chocolates, alcohol, and taxing activities should be avoided. Try to make sure she is eating, drinking enough water, and getting way more rest than she would usually need. Those exercises are to help retrain the brain on how to cope with the vertigo, and hopefully wont be required unless her case is more permanent. Figure out a way to keep her from throwing up all the time, ginger was a good suggestion. Perhaps ginger ale as it is more readily available. I recently thought I had a case without the vertigo and did a ton of research. Most of the doctors I went to had to look up what I was talking about. It seems to be a fairly widespread condition without much research on the matter because people often recover within a few weeks. Good luck