A 29-year-old man complains of recurrent severe headaches that usually occur in the early morning. Sometimes he is awakened by the headache "like an alarm clock." The pain comes on quickly, within 5-10 minutes, and it lasts 30 to 60 minutes. He describes the pain as excruciating and stabbing. The pain begins at his left nostril and is followed by severe retro-orbital pain. He experiences tearing and nasal stuffiness on the left side of his face. The patient thinks the headaches started when he was given a promotion at work 3 months ago and his stress levels increased. Which of the following is the best course of treatment?