It is your Blood Pressure you need to check. Your blood pressure can elevate with normal pulse rates. You need a BP cuff to measure your blood pressure. You can buy them at the drug store for $30 or so. The arm cuffs are more accurate than the wrist cuffs.

You may not feel nervous but your body/brain may be reacting to the situation in ways where only your BP elevates. Aircraft have sounds and vibrations that can over-stimulate your brain. There are visual clutter that can cause a problem with visual over-stimulation.

But then, the Mayo Clinic does validate air pressure related head aches.