I have experienced the shock sensation as well. It would trigger anytime I looked down while walking and almost incapacitate my thighs/legs. Mine went away about two months ago. I'm 9-mos out of radiation and chemo. Found out about it first by reading on this site.
Seems to me this is occuring in a higher percentage than 5%.

Weldon

SCC Stage IV , Surgery-Rad-Chemo finished 9/02