When the low back hurts, it's usually a combination of some or all of the components of the back. Injuries are either caused by one major trauma or many minor traumas that occur over time. If there is an imbalance, such as a rotated pelvis, a short leg or an increased or decreased curve in the low back, there will be areas of heightened tension that will be more vulnerable to irritation and injury. This is why it is common to feel multiple types of pain when injured. Muscles cause dull aches while nerves cause sharp pains.
Rehabilitation is the solution.
This can only take place if you know what the problem is and are willing to do what is necessary. No rehabilitation can take place until the pain and swelling are significantly reduced. Have the discipline to do whatever is necessary to get into the rehab phase as fast as possible, as this is the more active and less painful stage. So, stay out of work, quit running, give up bizarre sexual positions or whatever it takes for that 1-2 week period. During the second stage, begin slowly to rebuild a program.