I'm sorry that your question wasn't answered in a timely manner. We don't have many avian vets on this site. It's important to recognize that head tilt which is pathognomonic (specifically indicative) of vestibular (balance) disease may not indicate a peripheral (involving the inner/middle ear) vestibular disorder but, instead, indicate a central vestibular lesion located in the brainstem or cerebellum. In fact, bacterial ear infection is not commonly seen in birds. Instead, trauma, nutritional imbalance, stroke, and viral and fungal central nervous system infections should be considered. It can be a challenge clarifying the cause of head tilt in birds often requiring CT, blood tests and cultures of the choana and cloaca.
To answer you directly, if presumptive antibacterial therapy is desired, a broad spectrum oral antibiotic such as doxycycline or enrofloxacin should be considered. This will have to be prescribed by an avian vet whom you can find here: www.aav.org/ Please respond with further questions or concerns if you wish.