a 17-year-old boy presents to his pediatrician complaining of persistent drainage from his ear. he has a history of chronic ear infections and, one month prior, was started on amoxicillin secondary to symptoms of hearing loss and drainage along with physical exam findings of an inflamed, bulging tympanic membrane. when his symptoms failed to resolve, his medication was changed to amoxicillin-clavulanate; however, the patient is still experiencing symptoms. given his history and the persistence of symptoms despite antibiotic therapy, what diagnosis should be considered?