EMS arrives with a 42-year-old male who called 911 because of dizziness and nausea every time he tries to move. The patient states, "I feel okay when I lie perfectly still, but if I start to sit up, turn over, or move my head, the room starts to spin and I have to throw up." No past medical history. Vital signs: T 97.2°F, RR 16, HR 90, BP 130/82, SpO₂ 99%. Pain 0/10. What treatment should be performed?