I have had two separate bouts with extreme pain in the lower back down through my left hip, left thigh, and numbness from just above the knee to my toes. I have had this twice, so far, and the only thing that helped me was heat. The pain was 9-10 on a 0-10 scale and it was 24/7. I tried the cold treatments to no avail.
I tried a heating pad and it worked. I move the pad about starting with the area that "feels" most painful and then I will move on to the next spot as soon as the heat numbs the pain. It does not cure anything, it just relieves pain so I can sit, sleep, or live! The last round with the heating pad came in August 2008 and lasted through December 2008. I am still rehabbing my left leg.
The first time I had the pain I sought help from my GP and Neuro for 2 months. The last time I felt the pain start, I got on the heating pad ASAP. Even now, as soon as I even sense a pain "down south", I use the heat pad. I have not had severe pain since December 2008 and no continual pain since Feb 2009.
I hope you get some relief!