Hello Dave, Thank you for asking at HCM. After going through your history, I would first think of angioedema, an allergic reaction to some ingredient in the pizza. The ingredient can be anything, be a soy/tomato sauce, an olive, any specific spices, or some other ingredient. A 3-5 course of antihistamine like cetirizine or chlorpheniramine maleate will be helpful. I would like to ask you whether such reaction has occurred ever before. If it has occurred before, please try to find a common food ingredient. If this is the first time, it will be difficult to predict what caused the reaction because a pizza has lots of ingredients. Hope this will be useful to you. Wish you the best of the health. Regards.