--I highly recommend the Liza Jane spreadsheets:

www.lizajane.org

These were put together as comprehensive listing of tests that can be considered for neurological symptoms of various kinds. The spreadhseet format allows one to track results over time and look for patterns--and it also can suggest tests to physicians that they may not otherwise consider.

Can you tell us more about your situation? I'm assuming if they once told you that MS was a possibility they've found some evidence of demyelination on MRI, or abnormal protein in through lumbar puncture, but these can be present in other conditions. What has led to the current diagnosis?