Pain at the root of the left thigh can be caused by a variety of reasons, including lumbar strain, lumbar disc herniation, femoral head necrosis, injury or calcium deficiency. In this case, it is best to go to the orthopedic department of a regular hospital and have a film taken for examination. After the specific cause is identified, symptomatic treatment can be given under the guidance of the doctor. You should pay attention to rest and avoid strenuous exercise. If it is a lumbar disc herniation, lumbar strain, you can use physical therapy, hot compresses, massage, acupuncture are available.