Hi!  I have been playing golf for many years and have also experienced lower back pain on and off.  Low back pain seems to be a common injury for golfers but is definitely preventable.  Like any other sport, it is very important to warm up before you step out on the course.  My pro suggested that I start by stretching the most important muscles that may cause back pain including my hamstrings, hips and torso and then progress to taking easy practice swings.  He also suggested starting out on the driving range before hitting the course. Hope this helps!

Along with flexibility, strength is also important both in the lower back and the abdominals to help prevent injuries.  I found a website with some great exercises.  Check it out!  www.sportsinjurybulletin.com and search for lower back rehabilitation exercises.