Oh my god! I have the same pressure build up in my left temple! I wrote 'pressure build up in the left temple' into google and this was the best matching site because of your comment. I have been really busy but have to go see the doctor soon. If you find out what yours is or could be, could you message back so I know whether to panic just yet. I know every person and case is different but you explain the pressure exactly how I feel it!
Is Dr ordering brain, c-spine or what type mri? My first choice
would be a c-spine since the muscles & stimuli go from neck to
skull base messenging the trigeminal area at temple. A combo
of both is good to rule out things. If nothing shows up, perhaps
get doc to refer to ENT or have family doc order a Coronal CT.
Unilateral dryness sounds like a possible problem of the
function of your maxillary sinus. This area regulates mucus,
moisture to tissue in that sinus area. If it dries out it stops
relaeasing amount needed to keep sinuses moist. You don't have
to have drainage/infection/nose blowing. If maxillary blocks or
dries too much, it sends msgs to jaw & mostly temple causing
pressure buildup or pain. It's 'Tri' because it has 3 branches.
Ea. has other nerves that radiate out w/ different functions.
I know this part of the skull in my sleep. Come back if you have
anymore questions. Hopefully, it's just a nerve transmission from neck & muscle relaxants may resolve problem. Your sinuses
replace fluid every 30 min. That's why I think it's odd that
one side is always dry. Good-luck.