Peanut allergy question

I’m on a Cub Scout camping trip.. I let the leaders of the pack/den know that my son is allergic to nuts and tree nuts and they still brought peanut butter to serve as part of lunch. Obviously my son and I didn’t have any but some members did. A couple of hours later out of nowhere my son started feeling nauseous and couldn’t hold his body upright. He remained this way for about an hour or so and thankfully slowly started feeling better. I think he was showing the beginning signs of anaphylaxis. What should I do?