You have a nerve that is inside the tooth. Anytime you have a toothache it is the nerve that is infection. Not all toothaches are due to infection. You can have pain due to the possibility of a...
hypoglossal
Facial nerve (Cr. N. VII)
Optic nerve CNII
Vestibulocochlear nerve (CN VIII). More specifically vestibular nerve of CN VIII is responsible for equilibrium and balance.