Non-systematized chronic musculoskeletal pains are a frequent reason for consulting in general practice. The possible causes are numerous and sometimes nonspecific. In some cases, the etiologic investigation of patients with non-systematized and chronic musculoskeletal pain can not highlight any organic cause. Several studies have shown a link between these symptoms and vitamin D deficiency, characterized by a blood level of 25 (OH) vitamin D < 20.8ng/ml. This deficit is easy to identify and to correct through proper vitamin D supplementation with few side effects. Nevertheless, it remains unknown and vitamin D deficiency is rarely considered as a possible etiology in patients with chronic pain. We hypothesize that vitamin D supplementation in patients with non-systematized musculoskeletal pain and deficient in vitamin D could improve painful symptoms. We aim to perform a double-blind randomized controlled trial, vitamin D versus placebo, to assess the pain improvement after vitamin D supplementation.