I had this happen once also, worst pain, couldn't hear, but it went away by the end of the day. My son does great on flights, except when the pressure changes for landing, he cries and rubs his ear, nothing helps until we get of the plane, not gum, lollipop, or drinking. He is 6. We finally bought him the airplane pressure plugs, and it is a life changer for him. No more issues. You might want to consider them, I found them at Target, Walmart, and our local grocery store. They are also reusable and come in a handy case. I believe they say put in at least 30 mins before landing or you can wear them the whole time. My kids actually put them in and still wear their headphones to play on the ipads. However, we do have over the ear headphones.
kids 5&8)
. My DD(8)...who had past history of chronic ear infections, leading to tubes, always has a terrible time on plane with ears. Thank you for sharing! 
My DD wanted to know if we could drive from Washinton state (instead of fly) 
all because of the ears.
