Earlier this year, i presented at the er with a systolic bp over 180. before that, ive had a thunderclap headache and episodic hypertension. i have inapp. sinus tach, orthostatic hypotension and chronic nausea. could it be pheochromocytoma?

Unlikely - it’s rare: The symptoms you describe are consistent with that, but... that condition is extremely rare. Rule out more common things first. For instance: do you use caffeine, energy, drinks, or workout supplents? Start by eating a whole food natural diet and see it that helps. If you get more of those symptoms make an appointment with primary care doctor to start a full work up.