Good to meet you. Your experience is horrible, and I am sorry you find yourself at this point.
If there is anything to be found that may help you, this is the place to research it - check out both the Drug Pipeline, and Regimen Threads - you may find something either worth trying now, or that will give you some hope for the future.
I have had ms since about 1999, and although I still have relapses, my neuro is concerned that I am also becomming SP - so I share your concerns. I am on Avonex and also take a bunch of meds for neuropathic pain, muscle spasms etc. Fortunately, I get some relief from them - it may be worth trying other meds in the same class of drug (for pain relief) as different folks respond to different meds. I have tried a few so if you want to share notes, let me know - symptomatic releif, while not altering the course of the disease, can at least improve your current quality of life if the docs get it right. No one should suffer pain and my doc has been quite aggressive in finding a regimen that helps me (we are all different), so I have been through a few drugs...
Sure hope something starts going right for you real soon - all the best, and welcome to the site.