During descent, pressure in the cabin increases rapidly. If the tube that connects the nose and the ear is blocked because of a cold, allergies or sinus problems, it’s difficult to balance the pressure.
Ask the FAs to get you a hot cup, nicely though please and ask ahead of time because much as your FA's are there to help you with that, safety is their primary concern and there are things that they can't do while doing their safety and security checks with the passengers. So, don't be upset. As well, once you hear from the Flight Deck: "Flight Attendants be seated for Take Off/Landing". They must go sit and buckle up. So, again request ahead of time.
Anyhow, back to the topic. Hot cups will help. Hot cups are Styrofoam coffee cups with a paper towel in the bottom and a small amount of very hot water poured into the cup. Hold the cups over your ears. The steam will help the pressure stabilize and ease the pain.