Test your hip mobility. I often end up tweaking something on my right side of my lower back and funny enough my right hip tests out to have crappier mobility.
You might want to look into Good Mornings and Reverse Hypers. It can literally just be BW with a stick but lots of reps to get bloodflow into that area and move it around. Tightness sucks.
Expect it to take about 2-3 weeks, maybe a month. Typically stuff like hanging or supporting in L will suck too as will pike stretch.
Crapton of mobility. Leg swings, stretching, etc.