Suddenly, the patient screams in pain and starts clutching the side of his head saying he is having an attack. On exam, you wonder if he has a unilateral Horner's syndrome. You're not sure because he does seem to sweat. His eye is pretty red and you wonder about conjunctivitis. The patient can't give further history but says it'll get better within the next 15-30 minutes. The rest of the exam is unremarkable, except for a pack of cigarettes in his shirt pocket.
Challenge: Other than danger to self, what's the diagnosis?
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