What Causes Inflammation In Lower Back Radiating Down The Leg?

I have severe and sudden burning along what I assume to be a nerve in my left leg. It seems to start in my lower back (left side) and move around the outside of my hip and diagonally down to the front of my thigh to the inside of my leg and knee where it really lights me up. Stretching the leg straight can bring it on in a big way. In my searching the only info I find that seems close indicates the saphenous may be the culprit. The sciatica is mostly down the back of the leg, right? What do you recommend to reduce the pain and hopefully stop the cause?