I had this same type of problem. I tried every possible diet, supplement, and detox method you can think of. I searched for over 10 years for an answer. I went through an extensive homeopathic sequence to desensitize myself from any foods I might be allergic to. I tried a standard doctor, several naturopaths, chiropractors, and a homeopathic clinic.
I had this problem for decades. It got to the point where my whole day was: eat-fatigue, eat-fatigue, eat-fatigue. It happened with every conceivable food I ate. What finally worked was mud packing. I had a scar on the underside of my chin from a car accident that happened when I was 5 years old. I mud packed the scar one time, and noticed I felt a bit better. Mud packed it two more times and REALLY felt better. Like I haven't felt since I was in my teens. This was with Quantum Nutrition Labs "Medi-Body Pack" mixed with their Gallbladder-ND liquid. You have to go through a mud packing sequence that starts with your hands and feet, then up until you finally can mud pack your neck then your face. I was really shocked at how effective it was. You can search the internet and find instructions for how to do this. You could probably call qnlabs to get advice as well.
The idea behind the mudpacks is that your biofield (same idea they use in acupuncture) is blocked with an "interference field". The interference field redirects ("reflexes") your energy in a bad way to other parts of your body. In my case the chin scar was reflexing to my stomach. The mud packing clears the interference field so your body can behave normally. Sounds weird, but it worked for me.
I've read that any kind of scar or injury on your torso from your neck on down can reflex to your stomach. I had to do a lot of exploratory mud packing to figure out where the problem was.