I don't know what to say except oil of oregano is pretty strong stuff so putting it up the nose would probably not be a good idea.
Perhaps a better idea is to buy the tinctures of the herbs (herbs extracted by usually alcohol) which typically have better absorption. Maybe you could allow the herbs to soak in the mouth for a bit which would allow some penetration in that area.
You can buy the extract or make them yourself, make sure you use a minimum of 80 proof vodka. Do NOT dilute the mixture with any water.