, I can understand why you think the doc jumped the gun on an FND diagnosis--and yes, MS testing involves more than a brain MRI, history, and physical exam.
FND, according to the attached NORD article, is also known as conversion disorder, something that used to be dismissed as hysteria and all in one's head. But there are specific tests for this diagnosis. It's not a diagnosis of exclusion like MS. MRIs, blood tests and spinal fluid all test negative (normal) in FND, unless you have another disease that would influence the results.Here's the link to FND info: https://rarediseases.org/rare-diseases/fnd/
You might want to discuss FND diagnostic criteria with your doc, find out on what she's basing her diagnosis. Express your desire to have more thorough MS testing. That would include a C-spine MRI, evoked potentials testing (EPT), and a lumbar puncture. Feel free to seek a second opinion with another neurologist too, perhaps an MS specialist if you have access to one.
These things take a bit of detective work and you seem motivated to undertake it. I hope you'll keep us updated. Best, Kim