what causes muscle?
<answer> Muscle due to injury or overuse is most commonly localized to one area. <context> Muscle pain can be localized to one muscle group or diffuse, involving multiple muscle groups. Muscle pain due to injury or overuse is most commonly localized to one area. Depending upon the cause, muscle pain can be mild or severe and debilitating. Muscle pain is the hallmark symptom of some chronic conditions like fibromyalgia. Related symptoms that can occur with muscle pain are tenderness, swelling, redness, or fever. Medically Reviewed by a Doctor on 10/27/2014.