The dizzy speels sound exactly like the ones I had -- basically to one side that was worse than the other and almost passing out it got so bad.
I saw an amazing ears/nose/throat doctor who discovered that I had something wrong (I'll try to remember what he said and let you know)
but basically he put me in this chair that went back and felt as though you were going to tip over backwars while he examined my eyes and said oh yeah thats it.
He gave me medicine and exercises and to this day I have had no recurrences.
Good Luck and let me know how it goes with further tests.