A sudden allergic reaction?

XP from food allergy board.

At 5:00 last night as we were heading out the door, I noticed kiddo's eyelids were red, and he was rubbing them a little. When we got to the store ten minutes later, it looked like he had a mosquito bite on each eyelid, you know how a mosquito bite gets white and kind of welt-y? Looked like that. As I checked out and got him back to the carseat, they were getting puffier. We drove to the ER, at when we got there about 5:40, they were nearly swollen shut. His breathing was just fine, thankfully. They gave him benadryl, some steroids, a prescription for a steriod, and the swelling has gone down. We're went home and he slept peacefully all night.

The only thing that was different about yesterday, that I can think of,?was that I ate a handful of peanuts at about 4:30. Although I almost never eat actual nuts, I do eat peanut butter almost every morning. The doctor said that maybe the peanuts came from some mixed nuts, and so it could have been a reaction to another tree nut? From me touching the nut, and touching him??She said to follow up with our regular pedi, and maybe get a referral to an allergist, so I've got an appt with pedi on friday morning.

Also maybe worth mentioning, the last time I had nursed him was at noon, so whatever it was, I don't think it was in my milk.

I guess I'm not sure what my exact question is... just if anyone has any expertise/insight/or has had a similar experience? I realize that his reaction could have been much worse, but this was definitely my scariest mommy-moment to date.