Review Question - QID 109945

A 23-year-old patient with a past medical history of anxiety and appropriately treated schizophrenia presents to the emergency department for a 1st time seizure. The patient was at home eating dinner when he began moving abnormally and did not respond to his mother, prompting her to bring him in. His symptoms persisted in the emergency department and were successfully treated with diazepam. The patient is discharged and scheduled for a follow up appointment with neurology the next day for treatment, at which time he is started on a new medication. The patient returns to his neurologist 1 month later for a checkup. His temperature is 98.7°F (37°C), blood pressure is 123/65 mmHg, pulse is 91/min, respirations are 13/min, and oxygen saturation is 98% on room air. Physical exam is notable for carpopedal spasm when his blood pressure is being taken. Cranial nerves II-XII are grossly intact and his gait is stable. Which of the following is the most likely explanation of this patient's current presentation?