In some cases, medical treatment is required.
If you have already planned a flight and have severe pain even on the ground, you should schedule a visit with an ENT specialist to make sure you are not going to damage your eardrums.
If your condition does not allow you to fly safely, it’s always better to change traveling plans. The doctor can issue an “unfit to fly” certificate to use for insurance refund claim purposes.
The most important part is to be aware of your condition and assess in time the potential damage to the ear.
So next time you are flying over Rome, besides trying to spot the Coliseum, take a minute to listen to what your ears are trying to tell you with their pop!