'Chronic pain syndrome' is a very broad and not particularly well-defined term that refers conditions where pain is present several months past the time a doctors feels it should have been resolved. It's often diagnosed where it appears the structural problems have been resolved and doctors cannot account for the remaining pain. 

It appears to be associated with an upgregulation of the pain producing system in the body and is exacerbated by stress. Alternative therapies such as meditation and relaxation exercises can be prescribed for it but there's alot more work to do on its causes and treatment. Prominent disorders such as fibromyalgia, IBS, TMJ, interstitial cystitus and others are often associated with it.  

Researchers recognize CPS and its offshoots cause a lot of distress in our society and produce high economic costs.