Like you, I have been reacting very badly to all grains including wheat, rice and most starches, fruits, sugar. Cleared of diabetes, and have tested blood Sugar many times so I know it's not that. Within 2-4 hours of eating high starch or sugar, I crash horribly. My entire body feels prickly and numb and this doesn't subside for at least a day.
I dont react at all to animal meat either, in fact its one of the only thing keeping me going at the moment, along with low carb veggies and greens. If you figure out how to deal with adding back these foods, let me know.
A high-starch diet seems horrific at this point, as a small sweet potato will ruin me for days.