I have read all of these posts and have gained some valuable information. I, too, am struggling for a diagnosis. I am feeling frustrated and tired of the many specialists who cannot agree on how to treat or diagnose me. I have had facial flushing for years and have also now developed intermittent diarrhea, reflux, tachycardia, palpitations, dizziness, headaches, etc. I have had NUMEROUS labs and scans and the doctors are undecided about whether I have Carcinoid Syndrome with no tumor found, or Mast Cell Disease. My Chromogranin A has been elevated, my 5-HIAA have been elevated, with a normal Tryptase, normal Urine Methyl-Histamine, normal Prostaglandin D2, and an elevated/ High Plasma Histamine. It is super confusing and the doctors cannot agree. I am going to Mayo in October and am hoping for some clarity. In the meantime, I may go see an Allergist/Immunologist at Essentia to see if they can do any more testing. I am in Northern Minnesota, about 75 minutes from Duluth. I have self-treated with an H1/H2 blocker and Quercitin. I also have developed allergic asthma as an adult, just diagnosed in August, and am now on inhalers for the first time in my life. Thank you all for information and hope everyone finds answers.