Allergy Testing. If you are having symptoms that you believe are due to food allergy, you should be seen by a board certified allergist and have appropriate allergy testing performed to help determine if you are allergic and to what food you are allergic. If you suspect a specific food, stop eating it immediately.
It depends. It really depends on what symptoms you are experiencing. For throat tightness or shortness of breath call and ambulance or get to the emergency room. For skin rash you can take an over the counter antihistamine such as diphenhydramine. Either way it is best to keep a food diary and discuss the foods you believe are causing your symptoms with your doctor.