To be honest Katherine - and I'm an aromatherapist too - I've had this a few times, and nothing cleared it up better than antibiotics. As it's an infection of the inner ear and affects balance, it can make you feel really sick, so hubby can obviously inhale ginger, or citrusy oils. Aside from that if he hasn't been to the doc, I think he should.
Sorry can't be of more help, but having been there, I know I'd take anti-bs for it again.