Everyone is different but like the above post, my ds (3) has terrible ear pain on planes.
He has had "tubes" in his ears and still got infections. He has had fluid and no infections, etc. On our last flight to WDW last Oct. my ds was 2 1/2 and would not put the ear planes in his ears for our flight to MCO. My doctor did suggest the sinus medicine and we used it. He would not drink from a cup or eat to help with the pain. Upon our decent to MCO, he was screaming for about 45 minutes, sweating, etc and he was too bothered to do what would make him feel better. Finally, we landed and everyone, yes, I mean EVERYONE, knew us from the time we got off the plane to picking up our luggage, everyone knew we were the ones with the screaming child. By the time we picked up our car at National's EA, my ds started to begin to calm down and then was fine for our 9 day stay. Upon takeoff and landing back to NY he was fine. He had a well visit at the doctors the week we came back and the doctor looked and looked at his ear again and told me it was torn (a small hole). It had to be the plane since this poor child screamed for one hour and I thought he was really going to pass out. He didn't have any pain on our return since there was no pressure since the ear drum had a hole in it. It healed itself after about 6 months but took our trips to his ENT and audiologist visits to monitor his hearing and ear.
We are going to WDW this Saturday but my ds and I will be taking Amtrak and my dh and dd will be flying in on Sunday. This is not the norm, but just my story since you asked.
I am sure you will be fine.