A 22-year-old man comes to the emergency department because of a headache
that feels “like a screwdriver” going through his right temple and eye. He says that it has lasted for approximately 1 hour thus far, and rates the pain as a 9 on a 10-point scale. He says this has happened almost every morning this week, but he cannot identify a trigger. He also describes “watering of his eyes” and difficulty seeing during these episodes. Physical examination shows ipsilateral miosis of the right eye, but the remainder of the ophthalmoscopic examination is normal. There is no tenderness of the right temporal region
on palpation. Which of the following is the most likely diagnosis?