Have you investigated Tinnitus and Menieres syndrome?
Concentrating on meditating and keeping relaxed and still can trigger vertigo in some people, the over compensation of the body trying to keep still can cause dizziness and a feeling of falling. If I was you I would go for more visualisations, than meditations, with your eyes open and focusing on an object like a candle flame or a trees branches, the slight movement will help you to see the moment more clearly. Depending on why you are meditating you could try a led meditation too
I think the main thing to do is to not worry and perhaps go easy on the meditating till you have been to the clinic?