Yes, ROD is a factor. Having been grounded for nearly a year myself for this type of problem early in my career and having had two sinus operations to relieve the plumbing, I became well aware of it.
However, the first 10,000 ft are where the greatest change in air density occurs. Most airliners keep a cabin altitude below that.
The reason some young children yell on climb and descent is because of severe ENT discomfort. As they are more prone to ENT conditions than adults, I would get professional advice before flying a very young child for the first time.