The causes of pain in a spot on the left back may be carbuncle, myofasciitis, herpes zoster and so on, as follows: 1. Boils and carbuncles: boils and carbuncles are an acute purulent inflammation of the deep part of the hair follicle and its surrounding tissues, which can cause limited pain in the infected area, in addition to redness, swelling, fever and other symptoms. 2. Myofasciitis: long-term large amount of left back activities, maintaining poor posture can cause aseptic inflammation of the myofascia, when the inflammation causes muscle spasm, it can be manifested as a little pain in the left back, in addition to swelling, limited movement and other symptoms. 3. Herpes zoster: varicella zoster virus infection of the ganglion can cause a series of clinical symptoms, the typical symptom is a unilateral zonal distribution of the rash, pain. When the left back nerve is involved, left back pain can occur, which can be manifested as a point of pain in the early stage. Left back pain in a point may also have other causes, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.