How Can severe Anxiety Along With Diarrhea Be Treated?

I have had anxiety for some time but thought it was pretty under control. However two weeks ago while on a mini trip I had diarrhea. Assumed it was something I d eaten. Seemed to be ok the next day and began my flights home. Just before the last flight I began to feel nauseous and felt I should get off the plane as the doors were not closed yet. Stood up to tell stewardess and fainted. That got me to the hospital where the only thing they could see was a slightly low potassium. I checked in with my doctor the following week and he felt this was just a return of my old problem. He referred me to a psychiatric nurse practitioner. I could not see her this week. Every since that incidence I have continued to have periods where I feel lousy-for instance awakened in the night from a sound sleep feeling nauseous. Diarrhea off and on since I returned home Feb 28. Today went to gym for an hour. After having a bite to eat took a nap. Awoke dizzy and very dry mouthed. Went into diarrhea again. No temp. We are to fly out on a long vacation. I do know that flying stresses me so I usually take .25 of a Xanex. Would it do me any good to postpone the trip for a week.? Do you think this could be anything other than stress. Is it normal that physical stress would bring on these symptoms?