I have not heard positive things about botox and would never do it myself for pain relief. There are too many posibilities of a reaction or getting worse.
For myself I am very sensitive so even like a massage would make me worse and stir up the nerves rather then settle them down. Everyone is different but I think in general one has to be very careful of what types of treatment they do. I think working with a pain management doctor who deals a lot with this type of condition is key.
My NC test I can't recall how long it was. I also had an SSEP with the NC/EMG. It was stated that when the NC/EMG does not show etc that SSEP is done. I had both legs done though I do know that even though at that time it was only in 1 leg but then it spread to the other leg as well which my neuro said is common. Like I said though I have RSD as well.