I know how you feel I been dealing with same issues for over 3 years. however I did find that being tested for food allergies, including preservatives and chemicals / dyes was very helpful. I found almost 4 pages of sensitivity to food or allergic to foods that my body was not digesting properly. I also found testing for vitamin deficiencies was very helpful. After learning of this I was able to go on rotation diet of the foods I could eat. Also supplements to help with any vitamin deficiencies.
I was not gluten intolerant but wheat, soy, and many more allergies and intollerances up to about 4 pages.
I also had to talk with over 3 different GI physician before getting some medication that helps control my symptoms. It is still hard to get an actual diagnosis but at least I able to control my symptoms and feel better. This able to enjoy life a little more.
But like I said once I found what my system was intollerances too by pushing for and paying for blood work for the allergic / intollerances to several things. I found how to manage my meals and felt. A lot betterView Thread