Wow, a lot going on. Vertigo, walking imbalance because of it, etc. can often be due to inner ear dysfunction but it she's been to an ENT. So, assume they checked that. Is she diagnosed with Parkinson's? If she vomited when taking medication, that is not uncommon. You are supposed to take it 30 minutes before or 1 to 2 hours after a meal and with a full glass of water. People who have the side effect of nausea are recommended to eat soda crackers with it or some juice. If nausea persists, they often given a product to help with that -- supplemental carbidopa. And there are some different meds to try, dosing options, etc. Not sure if this helps but I'd continue to work with the specialists to help her feel better. Parkinsons is rough and slowing progression of the disease is the goal rather than cure which is always a mentally tough thing to acknowledge. But again, not sure if she was diagnosed with that.