How Safe Is Taking Correctol For Constipation?

Two years ago, I was successfully treated for a bleeding peptic ulcer. While I was suffering from it, it seemed constipation made the pain worse. Now my ulcer is healed, but I am constipated if I don't take Correctol once a week. After so much pain with the ulcer, I have become food phobic, and eaten only yogurt and Ensure since July, 2009. Please advise if once a week bowel movements are ok, and how to overcome the need for Correctoal without feeling constipated. (Since childhood, I've had one BM a week). My gastroenterologist did two colonoscopies (they were normal) and four EGD's. He laughingly said I have a tough colon (I guess meaning it's convoluted). Please help me to eat normally and have regular bathroom habits naturally.

Thanks,

Ginny