What could this be?

So I made the second doctors appointment, first doctors appointment and the doctor said it may be water in his ears. Now it’s been two weeks, but my nine month old suddenly started bumping his head side to side pretty hard, almost hitting his shoulders with his ears. I’m suspecting water in his ears but the doctor said it shouldn’t have persisted for two weeks especially with this hot weather and us going out for walks etc. he does it all day long?!! Anyone???