The sudden onset of left-sided lumbar pain symptoms can be considered first from the perspective of whether there is acute inflammation in the soft tissues surrounding the lumbar region. For example, acute inflammation of the lumbar fascia can lead to sudden painful symptoms on one side of the lower back. Acute fasciitis can be triggered by cold stimulation, or by trauma or exertion. In addition to pain, localized fascial inflammation can be accompanied by localized soft tissue stiffness and slight restriction of movement. It may also be due to prolonged twisting of the lumbar region or prolonged bending, resulting in slight misalignment of the small joints of the lumbar spine, which can also lead to sudden pain in the lumbar region, but most of them are accompanied by symptoms in the lumbar region. There are some patients with kidney stones who also have sudden symptoms of pain in the left side of the lower back. Therefore, after the symptoms appear, you should go to the regular hospital for relevant examinations in time to confirm the diagnosis.