A 28-year-old man presents to the clinic with complaints of severe, unilateral headaches that have been occurring for the past two weeks. He describes the pain as an excruciating, stabbing sensation located around his right eye. Each episode lasts about 45 minutes and occurs multiple times a day, often waking him from sleep. He also reports associated tearing, nasal congestion, and drooping of the eyelid on the same side as the headache. His neurological examination is otherwise unremarkable. Which of the following is the most likely diagnosis?