Lower back pain is usually across the lower back. The lower back muscles are tight. The pain radiates from the center of the lower back right above the tail bone towards the sides.
The tightness of the lower back muscles right above the butt hinders horizontal elasticity of the muscles required when one bends sideways. Bending sideways pulls these muscles. If they are tight, these muscles do not yield and are thus being pulled when one bends sideways.
Apply a whole lot of vapor rub across the lower back. I apply severe acupressure with my fingers to the lower back and the muscles above the butt. When I do that to someone, that person will feel instantaneously weak and collapse to the ground. Pounding at the lower back and the muscles above the butt with the fist, rolling a baseball bat or a PVC pipe or a rolling pin over that lower back and upper butt areas will all alleviate the condition.