If this isn’t an allergy what is causing it?

Patient: I was prescribed Otodex ear drops for ear pain, which contains active ingredients Framycetin sulfate, Gramicidan and Dexamethasone.After applying the ear drops, I experienced several itching inside my ears that lasted several hours. I immediately went back to the doctor who prescribed the ear drops, who said that it could not be an allergic reaction because Dexamethasone is used to treat allergy symptoms.I was not given any alternative for what caused the reaction or any further advice aside from “do not take Otodex in future”.I would have thought that I could have allergies to these medicines, even if it was unusual. If its not an allergy, what else might have caused the reaction?

Symptoms: Itching inside the ear where drops were applied