Check out food allergies - many don't show up in the normal tests but Dr.
Coca, a renowned immunologist, developed the Pulse Test to determine what foods
are causing you problems. If your pulse is more than 7 beats faster
after eating than it was before you ate, you have a food allergy to something
you ate. It can take a long time and a lot of effort to pin down the
source as some people find they are allergic to most every thing, but it can be
done. Here's the book by Dr. Coca on the pulse test: