It is true that vestibular problems are relatively rare in teenagers, the most frequent aetiologies for dizziness in childrens and teenagers would be migraine equivalent. However vestibular disorders may occur after : labyrinthitis, cholesteatoma, semicircular canal dehiscence...

Vestibular disorders in children. [Int J Audiol. 2008] - PubMed - NCBI
Cochleovestibular anomalies in children with ch... [Laryngoscope. 2008] - PubMed - NCBI
Prevalence of radiographic semicircular canal... [Pediatr Radiol. 2012] - PubMed - NCBI