Chronic back pain affects millions of Americans. Most, however, can’t identify the source of that pain. Neither can X-rays, tests, or other tools that doctors use to diagnose such problems. And perhaps unsurprisingly, most treatments don’t work. About 85 percent of people who report chronic back pain don’t have a test result to highlight a cause. They go through physical therapy and medication to no avail. But a new study suggests that a few weeks may be all that’s needed to unlearn pain. Most treatments for chronic pain operate under the assumption that it’s caused by the body. This new study was done under the premise that the brain can generate pain in the absence of an injury or after an injury has healed. By unlearning that pain, sufferers may be able to relieve their suffering. The study had very strong results. It involved 151 men and women who experienced …