The unconscious mind has total control over pain. It can turn up the intensity or turn down the intensity. By using hypnosis to ask the unconscious mind to turn down the pain level, great relief can be had in just one session. It is thought that nearly all back pain is caused by the emotions. Therefore, by releasing the negative emotions or beliefs, the back pain will subside completely.
Migraines are another tool used by the unconscious to make the sufferer slow down. Migraine is always a warning that you are doing too much and your resources are dwindling.
ME is used by the unconscious for the same purpose. The clients I have dealt with have always been in a state of complete exhaustion; usually because they haven't taken heed of the warnings given previously and are in danger of being open to dis-ease which would be life threatening due to lack of physical resources to deal with it.
Pain is always a warning, but can be radically reduced when it serves no practical purpose.