Bisacodyl and waves

I have been using bisacodyl laxatives for over a dozen years. Unfortunately due to the tolerance I my body has developed for this medication, I am often required to use between ten and fifteen tablets per dosage -- and I need to use them every night or morning. Since nearly the outset of my using this laxative, I have suffered from severe, intense, INTOLERABLE cramping of a degree I have never experienced with any other medication or from any other product. The cramps and pain are so severe that it is difficult for me to even put it into words. The pain emanates from just below my breast bone, in the center of my ribcage. It is so debilitating that the ONLY way that I can achieve even a slight degree of relief is to ball up a pillow or some similar object and place it directly where the pain is centered. The intensity can last anywhere from fifteen minutes up to and beyond an hour. It's made me late for work, for school, and is often accompanied by nausea, cold sweats and vomiting. I am seeking out others who have experienced these side effects after using this product to see what alternatives exist for me, and also to see how they might alleviate some of the pain. It is without question the most hideous, horrific pain I have ever experienced. Any thoughts?