A 49-year-old woman with a medical history of epilepsy presented to the ED 1 h after a single, 15-min, witnessed, tonic-clonic seizure. Over the preceding 6 months, she had experienced five similar seizures of shorter duration. There were no recent changes to her phenytoin dose nor had she started any new medications. The patient had traveled to Jamaica 3 weeks before presentation, where she smoked marijuana once but otherwise had not used illicit substances nor had she used tobacco or alcohol. She states she felt well during and after the trip until this presentation. While being evaluated by the neurology service, the patient complained of sudden-onset chest pain and cough with associated hypoxemia. She denied changes in her sleep habits, she had not experienced any fevers, and she had no changes in her exercise tolerance. The patient was admitted to the general medicine floor for further workup.