3 month old has a smelly ear!

My daughters left ear smells like something sour and although we have cleaned it with peroxide and a baby q-tip it still smells. We took her to the doctor last week when it started and they said her canals looked fine so no infection but couldn't give us any answer on what was causing the smell. We've washed behind her ear, in all the fold, everything! Has anyone else had this problem? My husband and I are lost at what to do now and don't want this girl to stink lol