Wow. You're quite the special boy, huh? I'm sure you and your Doctors have thought of anything and everything and you've done all those food logs and everything else... What a pain in the ass.
My money is still on food allergies though. For 30 years, I knew I had bad allergies (dust, pollen, mold, pet dander, etc), but thought I had NO food allergies. Turns out after my little trip to the hospital, the Allergy Dr. told me I have the single worse seafood allergies he has ever seen in 30 years (my Dad is allergic to seafood too). Interesting, since I had eaten seafood hundreds of times. I guess you can be fine over and over and over, but then one time - seemingly randomly - it could kill you.
My completely uneducated guess (I'm putting you on a hand here) says that you're allergic to something super common in food - like Wheat. I think you only react to it at certain times though, and probably in combination with another irritant, so GL figuring out what it is.
Dr. TP signing off.
P.S. I hope you have good health insurance.