Ikezu:
If you simply google "sinuses", you'll see a picture showing where your paranasal sinuses are located. Odds are your pain is over one or more of those spots. Each sinus has a small opening into your nasal passages to allow air to pass in and out. Block that opening, and the pressure can no longer equalize into the sinus, i.e. pain results when you ascend or descend rapidly.
A decongestant, either as a pill or as a nasal spray, can be very helpful if this is a recurrent problem for you. (Don't overdo it on the spray.)
Graham