Sorry to hear you are suffering and not getting answers.
In the past I too had seen different doctors for the same symptoms....it's a roller coaster! My suggestion to you, and I do this for myself, if stick with ONE doctor and if what he does for you does not help or the symptoms persist, then go back to that same doctor. Each doctor has their own way of diagnosing us and ruling things out, so you have to stick with ONE doctor and let them try a thing or too, and then perhaps they'd be more willing to send you for more testing if you don't get better. It's not often that a doctor will send you for a CT scan or MRI at a first appointment for headaches and dizziness.
I wish you the best! Keep me posted when you call and get that appointment!