I had multiple MRIs during my diagnosis, but for different reasons (MS wasn't suspected until after the first MRI). The MRI with contrast (which was the last MRI I got) didn't show anything beyond the non-contrast one I got first. Your situation may be different, but a non contrast MRI may show what the doc needs to see. Or you may have to go through multiple MRIs like I did.

Just food for thought, unfortunately it isn't very clear what you should do. I can offer you a hug and some sympathy - frustration seems to be the name of the game when it comes to diagnosing MS.