Hi, I too experience weird, scary breathing problems and a racing heart. I've had breathing problems for over 20 years, I went to the doctor who didn't know what was wrong and in the end my friend suggested I went to an allergy specialist who used a 'vega' machine to find out what foods I was allergic to. Although it took about 8 months to work out that I'm allergic to wheat, barley, barley malt extract, malt vinegar, I didn't get any breathing problems for a while, then one day I had some marmite and had another attack, so yeast and yeast extract was then eliminated from my diet! The main time of day when I get the attacks is in the middle of the night. They are very frightening and as a consequence I can't breathe in or breathe out - as you can imagine I avoid all the above foods like the plague, but last night I had another attack and I think I might now be allergic to cider vinegar as that is what was contained in the salad dressing I ate and can't think what else it could have been amongst the ingredients. This problem really gets me down, but I take anti-histamine tablets sometimes as a precaution if I've been out to a restaurant for a meal (which isn't very often due to the long list of allergies!) I would be interested if anyone else has had an experience like this and how you have coped?