2 weeks relaxing in the tropics got rid of my 'pressure' feeling. It wouldn't surprise me if some of those in Stilton's boat have middle ear tendon issues due to stress. Google for 'Tensor Tympani Syndrome'. Bear in mind that it's not as easy to confirm with tympanometry as most links imply. Stress / PTS-type problems also can cause the Stapedius to tighten. These conditions can also affect balance and create a feeling of pressure.
A 2-week course of Diazepam could be worth trying - if it helps, you could have a tendon issue. ONLY try this when you don't have machinery to operate!!! A 2mg dose for a fortnight shouldn't get you addicted; bear in mind this is purely for diagnostic reasons - DON'T start a tranq habit, BAD MOVE!