What Causes Nausea, Dizziness And Vomiting?

Several weeks ago I was at work and became dizzy (this was the second time this happened - previously treated for just ear infection and zofran). It continued through the evening. The next morning I was unable to be in an upright position because of extreme nausea, dizziness, and vomiting. Went to ENT that day and he felt that I had meniere s. I recieved a steroid shot in the office and had a 6 day course of steroids and was on zofran. After 3 days of the extreme symptoms, I recovered. A few weeks later I went for testing (electronystagmography and caloric testing) of which i had abnormalities. My ENT sent me for an MRI and the results came back that I had some excess fluid in the mastoid region, but the MRI was essentially normal. I havent heard from my ENT since. Any suggestions as to a diagnosis or cause.