Healing of pain from back problems should occur in the first six to eight weeks after injury. Pain that last beyond that time frame can become chronic pain. Often there's no known cause of the pain.
Long-term studies of back pain patients show at least half of all patients with back pain after one year will still have pain five years later. Some have bouts off and on while others have continual pain.
Researchers are trying to sort out who gets better and why. They are also looking for methods of treatment that work better than others. The treatment focus for pain that continues past the expected time for healing is different than acute pain. Treatment for chronic pain tries to shift the focus from pain to function. Improving function, not reducing pain, becomes the goal.
There are health care professionals who work just with cases of chronic pain. You may want to ask your doctor about any services of this type in your area.