Hi Victoria45
My Mum had an isolated but severe bout of vertigo about 10 years ago long before her diagnosis of Vascular Dementia.
Since she was diagnosed, she has very regularly complained of dizziness and when it is at its worst 'veering to one side'. This is accompanied by nausea.
She too has had her neck and ears checked, but Mum says (as far as she can remember) it doesn't feel the same as when she had vertigo before. The dizziness and accompanying nausea has been ongoing most days for at least 3 years, but despite all sorts of tests - neck, ears, blood pressure, heart, balance, eyes - no cause can be found.
As my Mum has a significant eating problem, I think that may have something to do with it and I have also tried to ensure she remembers to drink enough to prevent dizziness from dehydration. Either that or she uses the dizziness as a 'catch all' description when she's feeling under par and cannot accurately explain what's wrong (bit like a kid saying their tummy hurts).
Mum has a permanent scrip for Cyclizine - which she takes as and when she needs it. Her GP says it works for both nausea and extreme dizziness. It certainly seems to help Mum, although she needs reminding now to take the 'sick tablet' when her symptoms are troubling.