The commnent you made about your child's ears makes me think about a cold or other usually mild upper respiratory conditions. Do take her to the Dr. and see what is going on beforer taking her on a plane again.

I have seen young adults, even, experience tympanic membrane (ear drum) ruptures due to cabin pressure and possible pre-existing condditions as mentioned above.

Our grandchildren have been sick on planes, but they have been due to other ailments they have had that have nothing to do with motion sickness--asthma, migraine.

Gretchen, SC (not a Dr. or a nurse)