Reflex Sympathetic Dystrophy (RSD), also known as Chronic Regional Pain Syndrome (CRPS) can come about in many ways. Usually, it occurs after an identifiable incident like surgery, stroke, or injury (a torn ligament, fracture, etc.). Excessive pain continues afterwards and can be triggered with or without a stimulus. We can’t pinpoint precisely why RSD/CRPS occurs, but it appears to be a result of a malfunctioning sympathetic nervous system (which is a part of the nervous system that control injury sites).
Those who suffer from fibromyalgia can have mild to tense pain throughout their body – it’s a debilitating disorder which can affect muscles, joints and/or the skin. The pain is not necessarily centralized to one body part or area, and can affect different places at different times or all at once.