The best exercise is the "back bridge" as described by Matt Furey. I have'd 2 back surgeries with nerve pain. After 3 months my back pain nerve pain has gone away.
HOW TO:
Lay on your back, then using your hands push up of the floor and put the top of your head on the floor. Then rock back until your forhead or nose touches the floor. It took me 2 years and a Liver Flush to touch my nose to the floor. Hold the position for 3 min is the goal. Follow with a forward strech. 30 seconds 2 or three times a week cured me of back pain and eventually nerve pain.
It is truly a miracle exercise.