Have you been tested for lyme. I would proabaly get some blood work done and other tests to see if you have some microbe imbalances in the gut. If vitamins and herbs have the opposite effect on you then it sounds like bad bacteria or candida is utilizing it rather than your good flora.
Definetly sounds like some gut microbe imbalances going on. Have you gone through some extensive testing?
Interesting that you can tolerate grains and carbs but not fruits? What kind of carbs do you eat? What is an example of your diet?