What cranial nerve feeling a toothache?

Trigeminal (V) cranial nerve

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 cavity, gum disease, or even your wisdom teeth (the human mouth usually does not have room for wisdom teeth causing the to push against the teeth in front of them.

Do not wait to long going to the dentist as it can get worse and can get very expensive.

Hope this helps!