Stretching is key. The gluteus Maximus and minibus are often involved in lumbago pain. They connect to your hip and thigh. They are important in treatment here so make sure to give them a good massage and stretch, too. You may use a foam roller, ball, or hands to massage. If using a ball, try putting legs up the wall, back on the floor, and then ball under the glutes.
The Pigeon yoga pose is a great one for stretching this area. For this pose, you start on your hands and knees in box pose, and then bring one knee up to the wrist it was behind while bringing that foot attached to it to the opposite hip, and then resting your hips on the floor with the opposite leg outstretched long straight back behind the body. Make sure to do both sides to maintain balance.