I was vegetarian for a couple of years. I learned how to balance the food and do it properly. It was the absolutely worst I ever felt. At first I felt better because I stopped eating stuff like twinkies and candy all the time. Gradually I got weaker and weaker and more problems arose.
Generally folks with cfs/fibro & adrenal problems need a lot of protein and need to avoid a lot of carbs, especially refined carbs. We also need to avoid sugar, even a lot of fruit sugar. Everyone needs good fats. A no fat diet will bring trouble.
Digestive enzymes are a big help to me. I also felt it made improvement to add bile acid when I eat fat/protein. The only brand I could find is Jarrow.