Why does the inner ear imbalance make you throw up?

Quite literally. How come when we feel "confused", we start getting the need to expel the contents from our stomach?

I get that we get sea-sick because of "mixed signals" coming in to our brain. But why do we feel nauseous? How come the centre of the problem becomes the stomach, and not some sort of heightened sense of needing to find balance?

Hope this question makes at leasr some sense. Thanks!