Good for you for wanting to find the right answer! It can sometimes be difficult, especially if tests come back normal. Your doctor is correct though, sometimes the MRI's do come back normal in the early stages of MS. Did you have just a brain MRI? or was a spinal MRI done as well? Sometimes the spine might show something that the brain MRI won't. You can also ask about evoked potentials tests which test how fast signals get from the brain to the rest of the body.
Nystagmus is a common symptoms of MS, but it is also seen in other illnesses too like Meniere's disease and fibromyalgia. Have you ever had your magnesium levels checked?
Best of luck to you, and I hope you find some answers soon. Please come back and let us know how you are and how your new tests go.
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