Help ! I need a clue-pain after eating.

I feel very sick and don't know what to do. Here is my basics female, 46 taking synthroid for hypo (also added sups for t3 conversion), a bit overweight clean diet and lifestyle rarely catch colds.
I feel fine at times, but sometimes I will get an attack after eating. The pain is on the left side of my abdomen. There is irritation in my mouth and throat, burning or pins and needles in arms and legs, joint pain and back pain.
Most of my body hurts. Gastroenterologist found nothing but b12 deficiency. In the past have had reflux symptoms and rectal bleeding. I went on a low starch diet because I suspected candida. Now it looks like fat and salt are bad too. I feel beat up and depleted from cleanses.
At times I feel fine. That is when I eat very little and avoid stress.
I would like to know what is causing this. I have bad luck with doctors and limited resources. Could I have parasites? There is a doctor i heard of who specializes in parasites. It's not cheap. What if that isn't the problem?
I could see a GP or go to another GE. Any help would be great. Thanks. Tweet