Sciatic Pain?

I am in severe pain! it goes from my groin down past my knee on the right side of my body. I have had back problems for 7 years from a previous accident which broke my back (L1-L2 fused) and pelvis. And this is a new pain that I did not have the past 7 years.
I started getting this pain over two months ago but just the last week it has gotten so worse I cannot remain standing or sitting for more than a few minutes, I can only get the pain to stop by lying on my back. I am taking several pills (Demerol) also to control the pain but soon as they where off the pain reappears and it is unbearable at times. How does one get help with this as doctors only seem to want to give more prescriptions? Thank you for your comments.