Strengthening your back, together with a strong core, which includes the pelvic floor muscles, will help you enormously in reducing back pain.
Try these exercises: The Plank, combine the Cat/Cow stretch, Swimming (either on all fours or lying on the stomach), Swan (Cobra stretch) and Rear Deltoid Squeeze (known as the Dart). Main focus is on engaging the abdominal muscles, lengthening the spine and using the breath correctly!