I'm 65 years old and have always worked pretty hard. The last few years I have experienced pretty chronic low-back pain. I imagine that it is activity related. This last few months though, I have experienced a "clicking" feeling in my lower back, particularly if I am doing something that involves twisting my body. The pain level doesn't change with the "Clicking" but rather has a quality of instability asociated with it. Discs worn out?