A 54-year-old female with a 15-year history of schizophrenia presents for a routine medication management visit. She has been maintained on haloperidol for the past 8 years with stable psychotic symptom control. During the examination, the PMHNP observes involuntary, repetitive movements of her tongue, including protrusion and lateral movements, lip smacking, and puckering of her lips. These movements are not present during sleep. The patient appears unaware of the movements until they are pointed out to her. She denies any recent medication changes, substance use, or new medical conditions. Her Abnormal Involuntary Movement Scale (AIMS) total score is 14. Neurological examination is otherwise unremarkable, and there is no evidence of parkinsonism or acute dystonia. What is the MOST likely diagnosis?