A 16-year-old boy presents to the Emergency Department after striking the side of his head during a football match. He walked off the pitch unaided and recalls the event clearly. Since the injury, he has vomited twice.

On assessment, he is alert and conversing normally. There is no focal neurological deficit, no seizure activity, and no clinical sign of skull fracture. He is not taking anticoagulant or antiplatelet medication.

According to National Institute for Health and Care Excellence head injury guidance, what is the most appropriate next step in management?