I don't know Canadian disability law, so I am only guessing that you might be asked to get re-diagnosed. But, if the Canadian system is similar to the U.S. system, they will pay for it if you can show that you have a previous diagnosis. It could serve as a way to show any change in the progression of symptoms. Regarding your spinal problems (that is my disability, too), have you received (or been asked to receive) an electro-myogram (EMG)? It tests the nerve-muscle signal strength that can be decreased by spinal problems. My signal strength is decreased by 90 percent in my arms, and, to a lesser degree, my legs).
Good luck, in any case.