exactly what kind of tests have you had? You mention several of them, but do any of them include a BRAIN or CERVICAL SPINE (neck) MRI? If so, can you get the results of those and post them here so we can take a look? I would definately find another physician to take a look at you. There is definately something going on that warrants a Dr. appt. with someone who cares about you. I'd certainly consider a cardiologist first. GOOD LUCK to you.
Since you have had that problem so long, it would be an idea to go see a heart specialist just to have him check you out good. If that isn't what it is, he should be able to send you in the right direction. Since the other drs aren't treating you they evidently couldn't find the problem. The dizziness is not good, because it could be coming from shortage of blood flow. It could be more than one thing at the same time. I'd go with the heart dr first. High blood pressure can cause dizziness too along with headaches. Write down all of your symptoms so you won't forget any, and if you have access to have your blood pressure checked, I would. Keep record of it. Wish you the best