I have Sjrogen's syndrome and have the exact same problem. It took them years to test me for it…The only thing you can do is change your diet because doctors are clueless and can not help you. Also, one allergist said I have many allergies…yet I was tested by another one and they said I had no allergies. So allergy testing is not very reliable. Heart palps can be an indication of food allergy. Start a food journal. Sometimes I don't react for 2 days to something I ate. I am 62 and have had this since I was in my 30's. One thing that does help me is to drink a carrot juice and/or a green juice drink daily. I bought a hurom juicer and it's really easy to juice carrots with it. I use a Vitamix for my green juice. Vitamin A is supposed to help with mucus membranes.