I have been having back problems for the past 10 years but recently things have gotten worse. I had my first back surgery back in 2003 when i had a herniated disc problem. in the past six months i have noticed that my left leg started to bother me. i had some mild pain which i had ignored for a while. but last week it reached the climax. the pain got very intense and i could no longer put up with it.I had an MRI and i was told that i had a sciatic nerve. I have been taking different types of medications but they are not very effective. My doctor recommended an epidural injection which i had undergone 5 days ago but i have not seen any improvement yet. how long does it take before i can start to see progress?