What Could Cause Persistent Right Knee-to-foot Pain Unrelieved By Angioplasty Or Sciatica Treatment?

I've been having pain in my right knee for about 3 months, with aching from knee all the way into my foot. Th foot pain used to get better when elevated, but not anymore. I've had angioplasty, which did nothing for the pain. Am now being treated Sciatica, but that isn't providing any relief either. What else could this be?