Trish,
I just saw this post. I hope your daughter is doing ok. Valium is a very good drug for vertigo and dizziness. It's one of the first meds they put me on and I've been taking it for 16 years now.
I hope the doctor's find out what is causing this. I suffer from migraines also and they are very dehydrating and pure misery.
Take care. I'll keep you and your daughter in my prayers.
Hugs