It is not unusual to experience some lightheadedness or even to faint (a brief loss of consciousness) after an injury. This usually is caused by the trauma of being in an accident or being injured. This type of lightheadedness usually improves when you lie down and then gradually goes away.
Lightheadedness that does not improve or that develops after the initial injury may be a sign of a problem that requires evaluation by a health professional.
Vertigo that develops after a head injury may be caused by damage to the brain or inner ear. Vertigo that is so severe that you must lie down and lie still (no head motion) to stop the feeling of movement requires a visit to a health professional. Persistent vertigo after a head injury or a direct injury to the ear also requires medical evaluation.
WebMD Medical Reference from Healthwise