Head trauma that’s enough to cause a concussion can sometimes damage the vestibular apparatus in our inner ear (aka Labyrinth), which controls balance (see Diagram — Anatomy of the Ear). Episodes of vertigo, nausea & vomiting improve gradually over days to months, depending on the severity of trauma. Diagnosis is based on symptoms, and history of concussion, since all tests and CT scans, etc. are normal
There’s no treatment for Labyrinthine Concussion, it gets better on its own like all concussions. Some patients might wind up with Benign Paroxysmal Positional Vertigo (BPPV) or Meniere’s Disease. The more serious damage from head trauma that causes ongoing vertigo is a Perilymphatic Fistula.