The positional and movement demands of BJJ places a high amount of stress on the lower back. Although as you'll see, what's causing the pain, quite likely stems from an area other the back itself. As discussed in the "BJJ Strength & Conditioning: A Complete System?" article, incorrect alignment, activation or mobility in one area can cause a problem in another.
In this article, I want to show you the variation of potential causes, so you can start tackling lower back pain with a complete approach, not just looking at solutions in isolation. Too often people only target one potential cause. When you truly understand the root causes of any problem, it becomes much, much easier to fix it in a systematic way AND avoid the problem in the future, ensuring you can enjoy BJJ, feeling great on and off the mats.