A 58-year-old woman with Parkinson disease on dopamine agonist therapy for 3 years presents with a 2-week history of sudden onset of severe tremor, rigidity, hyperthermia (38.5°C), altered mental status, and elevated creatine kinase (CK: 2400 U/L). She admits to abruptly stopping her dopamine agonist 4 days ago due to cost concerns. What is the most appropriate immediate management?