Thanks so much for answering my questions, the other day and today.
Well, I am making some assumptions here since I don't know your entire case, but first off I will say that following up a bout of vertigo with a brain MRI is not good medicine (again, assuming we are just talking about a bout of vertigo). There is very little indication for this and one of the negative consequences was exactly what you are experiencing. Sometimes you find things that are likely completely harmless and you would have never known about them if not for an MRI... Now you're worried and your blood pressure is up. Frustrating.
Very likely this is a benign cyst/swelling. But, now that it's been discovered, there is some level of obligation on the doctor's part to weigh the pros and cons of evaluating it further. Bring your scan to an ENT doc.