Review Question - QID 213562

A 19-year-old woman presents to the emergency department with 3 weeks of throbbing and diffuse daily headaches. She experiences eye pain and pulsing in both ears when bending forward as well as frequent, brief "blacking out" of her vision upon standing, and occasional double vision. She has a history of major depressive disorder and acne. Her medications include fluoxetine, an oral contraceptive, and topical benzoyl peroxide. Family history is notable for a maternal aunt with migraines. On exam, her temperature is 98.0°F (36.7°C), blood pressure is 120/85 mmHg, pulse is 72/min, and respirations are 17/min. Her BMI is 29 kg/m^2. During lateral gaze testing, abduction of the patient's left eye is transiently impaired. Her strength, sensation, and reflexes are normal in all 4 extremities. Fundoscopic exam is shown in Figure A. A head CT is unremarkable. Which of the following is the most appropriate next step?