I WANT YOU TO LOOK INTO CHIARI MALFORMATION,it is often missed even on mri's exspecially if the doctor does not know what it is.
The other possibility is it could be a psychosomatic disease triggered by stress. How do you feel the moment you are stressed does it happen often or when you are stressed or paying attention to it? Learning stomach breath awareness can lower stress keeping your attention on your stomach ie filling the mind up with the thought of the breath and stomach filling up and blocking any other thoughts/feelings/moods out. That is the only thing that has helped me I have had my jaw locking and because it irritated me got worse ie it plugs up my ear similar symptoms and the more irritated I am the more it comes out, if I put my attention elsewhere such as my stomach breathing it goes away. I just know it takes away some or all (depending how I do it) of the energy from the ear if I do it.
i forgot to mention if its what i say it is it could be TMJ. If you want to know for certain buy some ear plugs at walmart cylinder foam ones and see if every time you have pressure its pressing on the ear and if it is then it is TMJ in one form. You could go to the sports section get a boxing bite guard and grip slightly (not a lot don't put tension but just enough to give yourself attention to the front of your mouth) everytime you have the urge to move your jaw or concentrate on the ear breath deeply from the stomach and concentratate on the stomach, eventually you will get used to not concentrating on your ear anymore and thus the pressure/energy won't go there, you'll also notice the pressure wanting to go there ie the jaw/ear turn to the gripping on the jaw and again turn your attention to the front mouth piece/grip of the jaw and start breathing and being aware of your stomach which will relieve the tension fron the ear/jaw.