High abd. Pain, flank pain, radiates to lower back, extreme fatigue, bloating, nausea, had low fever, sev adrenal innsufficiency. Sev pain, what's wrong?

Hazard a guess? You have "severe pain in abdomen, back, flank" in the setting of "severe" adrenal insufficiency. Is pain acute or chronic? Is your adrenal adequately supplemented? What tests have been run? What's been ruled out? Without this information i wouldn't hazard a guess, but would caution that symptoms as "severe" as you indicate require further evaluation ; treatment (perhaps urgently). Uti considered?