Hidden pain inside the left side of the waist may be caused by lumbar muscle strain, left kidney stones, female gynecological diseases, etc., which can be relieved and treated by lying down, applying hot compresses, and taking oral ibuprofen and other medications. 1. Lumbar muscle strain: long-term bending and exertion or prolonged sedentary, resulting in lumbar muscle tension, causing cumulative damage to the lumbar muscles, localized aseptic inflammation, occurring on the left side, resulting in the left side of the lumbar muscles vague pain, discomfort. Generally, it can be relieved by paying attention to rest, lying down and stretching the lumbar muscles. 2. Left kidney stone: when the left kidney kidney stone during the acute stage, characterized by hematuria, urinary abnormalities, renal area percussion beating pain intense and so on. Generally, it can be relieved by drinking more water, taking oral painkiller Ibuprofen and ultrasonic lithotripsy. 3. Female gynecological diseases: during the female physiological period, the main symptom of lumbar pain is a normal phenomenon, which can be relieved after the physiological period. However, pelvic inflammatory disease and cervicitis can cause long-term pain in the lower back along with a feeling of swelling. It is usually treated with oral antibiotics such as azithromycin. There are many reasons why the left side of the waist inside the hidden pain, the left side of the waist inside the hidden pain, it is recommended to consult a doctor under the guidance of the combination of relevant examination to clarify the cause of the cause of treatment, do not self-medication, so as not to cause adverse reactions.