It all seems a bit unclear as to whether there is certainty about the diagnosis or not. Maybe you could try and get them to establish once and for all how certain they are or whether there is anything else they think it could be.

I don't think I would be hoping it was SPS though - I know it feels good to have answers rather than having no clarity about what is wrong but SPS is a pretty nightmarish diagnosis and the treatment options are very limited. In the later stages, there is no effective treatment, care is palliative and it can progress to cause death. You just have to hope you don't progress and the symptom controlling medication is effective for you.

I'm not trying to be the merchant of doom, just honest. Having researched SPS because I was thought to have it, I know how bad it can be. They never confirmed what tests they did on me and the neurologist was clueless so there is a slim chance I could be living with it and not even know! I'm not into giving out sugar coated platitudes but I do sincerely hope that you get an improvement from the latest treatment they are offering. There is some decent info on the web about SPS and you might find it is helpful to do some reading so that you know what other potential medications could help.