A 49-year-old male patient presented at our clinic with back pain due to an insignificant injury that had occurred approximately 7 months earlier. Although the patient had been treated at primary clinics, the pain had gradually become aggravated and characterized by resting and night pain. We initially diagnosed the patient with myofascial pain syndrome and began treatment comprised of trigger point injection (TPI) on the back muscles to control the pain. His symptoms improved after the first treatment (TPI), but he complained of back pain again several days later. At that time he also reported that he had lost 10 kg over the 4 months preceding his initial visit. Plain radiographs of the thoracolumbar spine revealed L1-L5 compression fractures and generalized osteopenia. The patient was then diagnosed with multiple myeloma based on the results of a bone marrow biopsy. This case demonstrates the importance of using comprehensive diagnostic approaches when the patient manifests symptoms that are unresponsive to conventional treatment.