I agree with IBake. I have the exact same problem. I only once had the excruciating pain that left me unable to walk (bending down to pick up my shoes) and it has been a constant chronic low grade pain ever since. Some days are better than others. This happened in 2005. In 2006 I saw a nuero surgeon who confirmed the degeneration of the disk (also noticed signs of a fracture in a facet joint which may have contributed to the start of the problems many years earlier). At the time he advised against surgery, and that over time the disc will wear away and the vertebrae will fuse. Just 'adjust your lifestyle' and strengthen the core to aid stability.
Well 4 years on, and I have had NO change, and the pain is getting increasingly, worse. but still manageable. At the end of the day it is just becoming a huge annoyance. I am also waiting for the day that it 'goes' again. Went back to the surgeon this past weekend. He now believes that I should have ALIF (Anterior Lurabar Interbody Fusion) surgery. Weighing up that choice currently.
So, I agree you should see a surgeon. If you are having movement in the vertebrae in addition to the degeneration you need to find out sooner than later.
Good luck with it.