Parasites, or more directly worms. It's unthinkable, but very possible.
These things can lock up your bowels and cause all sorts of havoc inside your body, and impeed normal organ function, such as adrenals, thyroid, gut, etc.
I am just throwing the suggestion out there because this happened to me. No gas, no BM, no nothing for an extended period, then the unthinkable happened....after taking raw garlic for the bloat, I expelled worms and my saga began.