I really think you should consider adrenal function testing. It can cause nausea, POTS, fatigue, frequent urination...frankly everything you list. I too have some similar symptoms and just asked about it myself. I have a ACTH cortisol/cosyntropin challenge test set up for Thursday first AM. Your mention of the adrenalin rush might be key. They always test adrenal function first am because cortisol increases as soon as you start moving in the morning.