Probably a nosy question on my part, but have you ever heard of a fermented milk product called keifer? It replenishes the natural gut bacteria our bodies need to fully digest our food.
The only reason I ask is that your statement about falling off the wagon & feeling like crap after eating carbs sounds a lot like my situation, but since I've been drinking keifer, the sensitivity to wheat and other grains have pretty much disappeared.
I don’t do kefir but we are huge probiotic fans. We eat whole milk, plain Greek yogurt and add probiotic capsules as well.