I have for the last three months experienced these same symptoms. A simple sip of water in the morning activates abdominal pain, throat constriction and sweating and flushing of the neck and face. I have had ct, endoscopy w biopsy, gallbladder ultrasound, 24 hour urine test and multiple comprehensive blood tests.
No conclusions. Symptoms appear very prominent at end of day early evening. That seems to indicate as body processes more food or drink they increase. Blood pressure fluctuation occurs primarily dropping to 90/60, subsequent cold fingers and toes. Returns to my normal after hour or so. Weight loss after first 8 weeks has stabilized at 14 pounds after I decided I better eat, smile. Mayo, I am in the cue for last three weeks but wait is at least until mid January. I would add that locally one physician is concerned about carcinoid syndrome. Attempting to receive nuclear medicine test or PET scan to rule out tumor. Very difficult to forget being told tumor is a possibility.