I have had surgery for my diverticulitis, and once again have a couple of diverticuli back. I agree with CalGal. Have you gone to the bathroom??. My doctor lets me take Mirilax which is gentle. i also drink alot of water if I feel it coming on. And try staying away from lentils (if you like lentil soup), a killer for me. Eat seeds, nuts, beans, in small , small amounts if you must.
Most of the colon cleanse products contain some form of senna or other product that is a anthraquinone-like compound. Anthraquinone is a stimulant laxative which works by irritating the lining of the colon to promote 'emptying.' I really don't think with diverticulitis a stimulant laxative would be indicated. Check with your doc.