Wow, Zenlad! I can't imagine how traumatic and energy-zapping that must have been. Thank God things have improved now. At least with Cambridge you know you're getting the recommended about of iron each day, but I guess you probably need more than most! You poor thing.
I completely back up (no pun intended) Quiff's recommendation of psyllium husks. I add a teaspoon to each shake and have never had a problem. I bought mine on ebay, so you've got a variety of sources to choose from. If I remember rightly, it's cheaper than the Cambridge powder or medications, and it doesn't have any calories: its sole purpose is to add "bulk" to your intestine. I go less frequently than I did pre-Cambridge, but the only real toilet change I've seen is increased urination due to the sheer amount of liquids I pump through my system each day!