Sorry, I didn't notice the "D" part of your post. Magnesium would make it worse.
You might look up info on The Specific Carbohydrate Diet. It is for people with celiac, gluten intolerances, crohn's, etc. I had the book many years ago(hoping it would help the fibro)but gave it to a friend who's son was in the hospital with I think crohn's. She was eventually able to manage his symptoms with the diet and get him off of some of the horrible meds he had to take.