As a lay person having GI issues for many years, I Can only offer my attempts to help. I recently have understood that anxiety does play a part in constipation, so look into that, as I am doing now. I can't imagine, after all those tests and examinations that there is still no diagnosis/prognosis But at the same time, with my experience(s) I understand and believe you. Recently I have turned to....believe it or not: liquid AloeVera. I'm still trying this out, but I can tell you that using it as directed, I am less constipated. Now, as for me, I only stay with one "fix" for about a weeks time, then, for example, I am now using prunes/heated prune juice...for only a weeks time. I fear using anything consistently, the body becomes immune and no longer reacts to that particular aid. But that's just me. Your experience(s) leads me to confirm that the medical people are still in the realm of medicine being an ART, not a SCIENCE. I say that with respect to the industry because our bodies are very complex. So, ANXIETY, and other supplements are my current battle. Booze, drugs will only make life far worse than our GI. I am also taking CHAMOMILLE capsules to relax the gut, Beano, Fodmap, Miralax..etc
DONT help. One more thing is simethecone pills. Again, whatever I take is in MODERATION. There just isn't a "magic bullet". Perhaps over the years, we have depleted the "good bacteria" in our gut, trying to rebuild it isn't easy. Best of luck to you. PS: WALKING after eating seems to help.