I have experienced constant dizziness for months on end that turned out to be related to anxiety. No doubt about it, for when the situation I feared was over, the dizziness was gone instantly.
However, I have also had other episodes that were related to inner ear problems. They tended to come and go, though not so dramatically as episodes of Meniere's, for example.
If you have not yet seen an ear, nose, and throat doc or a neurologist to be evaluated for inner ear problems, it sounds as though it is time for that. Two years is long enough. There are tests that can be done for inner ear function as well as for certain cranial nerve problems.
Is it a constant thing, or does it have a kind of pattern to it?