Mysterious allergic reaction

from June--Here's Connor at the beginning of a bad allergic reaction to....something we weren't able to identify with allergy testing. This day he'd had nothing unusual or new to eat, but he had this scary reaction. We had just arrived home from taking Ethan to an appointment when I noticed these welts and saw that his face was beginning to swell. I snapped a couple of quick shots as I loaded everyone in the van to head to the pediatrician's office because Connor has had strange but pretty severe "mystery rashes" before that disappear by the time we get to the ped's office. Well, this day what you see here got MUCH worse. I did not need these photos because as soon as the staff saw him, they said, "Oh, wow! Ok, we'll get him right in." His face was all swollen and he wasn't smiling as much as he is in this picture. The swelling and welts happened on his neck as well. It got progressively worse during the first hour. I didn't take pictures when it got to the worst point...mainly because I had three children in a doctor's office, I left the camera in the van, and I became more concerned when the nurses called the doctor to come in right away to check his breathing and said the word anaphylaxis!!! Not a word I wanted to hear!!! I DID have his Epi Pen with me, but it was just precautionary, I was thinking. I thank God we did NOT have to use the Epi Pen and his reaction, which got much worse before it was better eventually went away without even a dose of Benadryl or anything....while we waited in the doctor's office with the doctor checking his breathing and listening closely to his lungs. He never had any problems breathing at all. The nurses were nice enough to mention that the testing they were about to do was very expensive so I might want to pre-authorize with my insurance company....which I did and thankfully almost all of it was covered. Phew! The ped that saw us that day said she was getting ready to fight an insurance company if they didn't cover it. She was worried about him and even called unexpectedly that night to check in on him at bedtime just to be sure all was well. Have I mentioned that I really love this practice?? Anyway, it was another exciting afternoon at our house and thankfully that is the last we have seen of any kind of reaction. Unfortunately, the allergy testing showed nothing. That's good that the testing was normal and showed no allergens, but without the tests pinpointing a specific allergen, we have no idea what caused this rather dramatic reaction???? Any thoughts from other moms with kids with allergies? I'm stumped! Anyway, that's our latest allergy scare. Now I know Connor looks adorable all swollen with welts all over his face. :) ....something I don't want to see again!!!!