Would the body be exhausted trying to fight of the infection from its own strength, when it actually needs the help of antibiotics? And as ears and balance are related, could this result in vertigo, hence nausea?
If you have middle ear infection (aka otitis media) and it not treated with antibiotics there could be some really nasty complications. There is a possibility of developing meningitis and brain abscess. Another nasty complication of untreated otitis media is mastoiditis. The prominent bone at the back of the ear, it contains air cells which communicates with the middle ear. Infection here may cause facial paralysis, meningitis, brain abscess or thrombosis of the adjacent venous sinuses. You will certainly have severe hearing loss or even permanent deafness. The inner ear which contains the cochlea, a coiled fluid filled structure which control balance is also nearby and can get involved in a severe case of otitis media and may lead to vomiting, vertigo etc. But those will be the least of your worries if you have meningitis, brain abscess or thrombosis of the venous sinuses. So if yourself or somebody you know has otitis media, better see the doctor as quickly as possible.