The persistence of pain memory can outlast beyond it’s beneficial function.
Chronic pain is pain that continues after an acute injury heals or after the passing of a period of time that should allow for healing. Often, for unknown reasons, the nerve fibers continue to send signals to the brain after this period, as if there is damage that needs attention. So, the signals never actually got switched off.
Several studies, mainly in the USA  , have shown that hypnosis can help you reduce the pain if not make the pain sensation disappear completely with no side effects to you and most probably at a much more reduced cost to you as well.
Mark Jensen and David R. Patterson “Hypnotic treatment of chronic pain”. Journal of Behavioral Medicine 2005
Tiara Dillworth and Mark P. Jensen “The role of suggestions in hypnosis for chronic pain: a review of the literature.” Department of Rehabilitation Medicine, University of Washington 2010