The only severe constipation (as opposed to regular, chronic constipation) I have had was due to a dose of Melatonin that was too large for me. I now take 150 mcg a night, which is a ridiculously low dose, but the right number for me.

I think if I ate too much beef or chicken, or anything really dense, or any grains, I would get constipated; so I eat sparingly of some of none of others. I eat loose foods (porridges, soups) and whatever cooked veggies I can tolerate. I drink a lot of warm liquids too -- that helps move things along.

I think you should get really creative with your diet if you haven't done so yet. Some of us just can't digest what is considered "food" by most.

I don't think those drugs would work for me: my gut is too weird and sensitive.

Other things to consider -- the right fiber and the right form of it and slipperly elm inner bark powder. I make a "first thing in the morning" tea from it. It supports the mucosa and helps things to slip along one's gut.