A 46-year-old man with a history of diabetes mellitus and chronic alcohol use presents to the emergency department with lower back pain that has progressively worsened over the last five days. he denies a history of trauma. on examination, he has a temperature 37.9oc (100.2 f), heart rate 87 beats/minute, and blood pressure 146/75 mm hg. he has tenderness with percussion over the midline lower lumbar spine. achilles and patellar reflexes are intact. he has mild decreased sensation of both feet, but his strength is intact. what is the next best step in management?