Possible Carcinoid?

Hi, i am a 25 year old white male 6'2" and 260lbs. For over a year now i have had facial flushing mostly daily which seems to be triggered at certain times of the day and also the usual triggers of alcahol (alcohol) along with this i sometimes have sharp pains in my right upper abdomen, stress etc. I also have suffered from GERD for two years and have chest pain and gas with this but no heartburn. I was referred to a endocrinologist a few months back and he ordered 2x 5hiaa tests.. After a few weeks of waiting i received my results and a letter from the specialist saying that both 5hiaa test levels were normal so this rules out Carcinoid as a possible cause of the flushing and seeing a dermatologist would be a good next step. I can not help thinking however that the 5hiaa test is not very accurate and maybe it missed something.