Have you considered your symptoms could be the result of yeast/fungus overgrowth? (What does yeast do to bread??) Gas, bloating GERD, constipation, diarrhea, rashes, psorriasis, etc. can all be attributed to yeast overgrowth. Maybe an antifungal diet would help. www.knowthecause.com
outlines a phase one diet (under the resources tab at the top of the page), as well as the part fungus plays in our health problems. This diet has helped me tremendously. I don't have to follow it so strictly now that my colon has healed, but I still find bread and other yeast products make my stomach balloon.