My 16 Year Old Son Has Idiopathic Anaphylaxis. He's Had

My 16 year old son has idiopathic anaphylaxis. He's had 2 major episodes within 1 year apart. He hasn't had an anaphylaxis reaction in 1 year now but does get white welts on his upper torso rather often. I had wondered if these episodes were brought on by binge drinking the night before but the welts seem to last up to a month. Recently Ive noticed he may feel nausea after excercise...could it be the elevation of his heart rate causing both?