Unlike acute pain, chronic pain does not serve as a protective mechanism. Chronic pain can be considered a disease. When you experience chronic pain, there may be no rhyme or reason to why you experience pain. You can no longer figure out how to get away from the pain and remove the damaging stimulus.
For example, back pain left untreated often shifts into the chronic state and it is there constantly. You may find that medications or other treatments are less effective and you cannot evade the triggering factors. There is a reason for this. Since acute pain initially serves as a protective mechanism the body makes a huge effort to let you know that the pain is there. By doing so, the body will lay down more receptors in the area that will be stimulated to let you know that there is a damaging stimulus is there. This phenomenon is known as Receptor Field Enlargement.
On-going pain will also make your body become more sensitive to painful stimuli making it easier to be irritated. This phenomenon is known as Peripheral Sensitization. Chronic pain also causes the spinal cord and brain to adapt causing the expression of pain to be more vague and abstract. This phenomenon is known as Central Sensitization.
These terms have probably already escaped your short term memory. They were brought up to bring to your attention that the neurology of your body changes in the presence of long term pain, re-enforcing the fact that chronic pain is a disease. It is important to take care of the cause of your lower back pain and not let it persist into a chronic state.