Suggest Treatment For Radiating Pain From Spinal Cord To The Leg

My father is 45 Years old, earlier it started to pain in legs and then later the pain started in spinal cord lumber area and burning sensation in leg , so he consulted to doctor , and in xray we found that there is no gap between L4 and L5 .
and the doctor gave a medicine like medrol, norflex,,,, but still there is a burning sensation in left leg and if he walks a little there vl a lots of pain in lumber area backbone,,,,I would like to know from know what is the cure for this pain ,, and how to start with , please help me .....I will be thankful to you