I know how frusterating this can be. It is a long and confusing road. On one hand you want to rule everything else out, on the other you don't want to slow the process.
What pain medication do you have? I think that will help us to be able to answer your questions. For instance, Brooklyn's neuro did a trail of her on Gabapentin...which is for neurological pain (i.e. if she was doing better on it, that would be a good indicator of SM, but if she was not doing better it did not mean she did or did not have it, it just helps us to better understand). A generalised pain reliever might relieve any pain, but I would assume a neurological medicine like Gabapentin (or others similar) would point you more to neuro pain and it would not eliminate pain from say, a hurt leg.

I could be wrong though...others are much more knowledgeable about this than I am so I will wait for them to chime in.