After all these 'remedies' I have one even easier to use. My DD had ear problems and ear vent tubes all her childhood. She met a doc last year that gave her some welcome advice to prevent just what you are asking about. He told her to plug her nose , close her eyes, and blow hard. It will eventually make her ears 'pop' and with out drugs or anything hazardous to her hearing. Do this about once an hour through the day and see if he doesn't fix the problem himself. If it is painful to do, get him to an ENT asap.