Your body is a self-healing machine
Most instances of non-specific lower back pain will heal themselves without the necessity for medical intervention if given enough attention to recovery. Back pain should be closely monitored and any actions that could exacerbate your pain should be avoided; other than that, it is recommended that you carry on a light schedule of motion to prevent the stiffness, loss of muscle and flexibility that actually slows recovery. Movement helps maintain range of motion despite the injury and also contributes to better circulation to keep the nutrients and oxygen flowing to the injurious region that is most in need. Four weeks is a good threshold for self-care; if back pain persists beyond this point, it may be worth investigating your condition further with the help of a medical professional.