Dulcolax
"I have been so constipated I took 2 pills Sunday night.  I started to have cramping a couple hours later. The cramps were getting so intense it felt like labor pains.  I went to the bathroom about  4am it all started. I was in bed or in the restroom all day Monday and felt weak and like I was coming down with the flu. This stuff definitely works but cramps are HORRIBLE!! I'm still cramping but now able to get out of bed on Tuesday but still visiting the restroom often. If I eat or drink anything I start getting cramps and have to go to the restroom. It's 3am on Wednesday and I've been up for a couple of hours with cramps and still going to the restroom. I'm getting to where I don't wanna eat or drink because I'm tired and want to sleep!"