need massage and torso movement to produce movement

Starting about 5 days ago, I began having cramps in my lower abdomen when it is time to have a bowel movement. This is not normal for me as I usually just experience a feeling of "needing to go," but without the accompanyment of cramps. I typically have one bowel movement a day and normally in the morning. This routine has not changed. However, while normally, when I sit down to go, I go immediately, now, with the onset of this cramping, when the cramps begin, I sit down to go and instead of having a bowel movement immediately, I end up sitting there for quite a while. In fact, in order to have the bowel movement, I have to massage my lower abdomen and/or rotate my torso back and forth in order to actually produce anything. And, unlike a normal bowel movement where everything comes out at once, it comes out intermitently with the need to repeat the excercise of massage and torso movement until I feel as if I am done. I should also point out that the stool is very soft. So, it is not as if I am experiencing the typical symptoms of constpation with a hard stool. What could be causing this and what are possible treatments?