We report a case of a 47-year-old male who presented with concerns for a "mass" on the right side of his chest and low-grade fevers for the last month. The patient was found to have an induration, erythema, and warmth at the right sternoclavicular joint, with tenderness to palpation and pain in the movement of the right arm. The patient was found to have septic arthritis of the sternoclavicular joint based on CT imaging. Sternoclavicular joint septic arthritis is a rare diagnosis and accounts for very few diagnosed septic joints. Most patients have some sort of risk factors, such as diabetes, immunosuppression, rheumatoid arthritis, or intravenous drug use. The most common pathogen isStaphylococcus aureus. Our patient did not consent to joint aspiration for a definitive diagnosis of the causative organism and was therefore empirically treated forS. aureuswith trimethoprim-sulfamethoxazole. The patient also did not consent to any surgical management. Septic arthritis has been successfully treated with antibiotic therapy alone in the past, and in conjunction with the patient’s choices, this was the treatment plan that was chosen for the patient. The patient responded to antibiotic therapy and followed up with a thoracic surgery clinic outpatient. This case depicts the importance of retaining a high index of suspicion for a rare diagnosis in the emergency department (ED). This case also depicts the successful treatment of sternoclavicular septic arthritis with outpatient oral trimethoprim-sulfamethoxazole, which, to the best of our knowledge, has not been done previously.