I imagine it would be difficult for your body to heal if you keep aggrivating it with foods that give you an allergic reaction. You might wish to try a Rotation Diet for a while to pin-point what you are allergic to, so you can omit those foods from your diet.
Getting the mercury fillings out will help greatly obviously, and doing some cleanses after your last filling is removed. And please avoid all sugars and refined/processed grains!! I know it's hard, but isn't it better to FEEL HEALTHY again? Eat lots of raw fruits, veggies, RAW fats, and juice everyday. When you start feeling better start to add WHOLE grains back into your diet slowly, like slow-cooked oatmeal, wild rice, buckwheat and quinoa.
Also, you may have a PHOBIA of throwing up, instead of it being related in anything physical. Google "Emetophobia" and see if what you read sounds right to you.