I have always felt dizziness when smoking cigarettes. If I smoked 2 in a row, then, it was hold-on-to-something, careful-not-to-fall-over-on-the-street dizzy. I get slightly dizzy with e-juices, but not nearly as much.
I would switch juices, maybe try a couple different brands, and see how they make you feel. It could be a brand thing. And, of course, lower the nic %.