It sure sounds like it could be an allergy to me. My daughter is extremely allergic to beans, peas, peanuts, tree nuts, and sesame. When there is an allergy to one of these things, it is fairly common to have, or develop, an allergy to one or more of the others - they are related. According to our doctor, symptoms to watch for are: Difficulty breathing, hoarseness, swelling (of eyes, lips, tongue, or throat), itching, rash, coughing, nausea, cramps, fainting, paleness, blueness, or vomiting. Initial symptoms may appear within a few seconds or up to two hours after exposure. Also, it is important to know that just because the reacion is vomiting one time, does not mean that the next reaction will be vomiting again; instead, it could be difficulty breathing - you never know from one reaction to the next what it will be or how severe it could be. I would have allergy testing done as soon as possible from a board certified allergist and not expose him to any of these foods until you know for sure. Also, keep Benedryl close by (use it if you see any symptoms) just in case until you get the epipen. My instructions have been to use the epipen if I see swelling of the eyes, lips, tongue, or throat, or if my daughter has difficulty breathing. Good luck to and your son. I would be happy to help if you have any more questions.