Sounds like an inflammation at the pituary gland which would explain the nausea and the connection to the vertigo, meaning an inflammation at the vestibular nerve. Most likely hereditary, it will go away on its own but will come back unless is dealt with.
If you ever worked too much and felt nausea, your pituary glad was most likely inflamed, if you felt nausea after eating, it was your pancreas, why the Pancreas? I still haven't met a doctor who would explain it.