A 28-year-old man presents with a 5-year history of insidious onset low back pain and stiffness. He reports the pain is worse in the morning and after prolonged rest, but it improves with activity. On physical examination, lumbar spine flexion is limited, and the Schober’s test is positive. Chest expansion is decreased to 1 cm (normal >5 cm). Pelvic radiographs show bilateral sacroiliac joint sclerosis and fusion. Which of the following is the most appropriate initial management for this patient’s condition?