There are two possibilities for this. Either you are not nearly hydrated enough...the bentonite/fiber requires a lot of water to be consumed with it, and that is in addition to your daily water intake which should be 1/2 your body weight in ounces of water a day.
The other possibility is that the herbs were stimulant laxatives that have resulted in problems with your bowel muscle and lead to constipation. These types of cleanses often result in dependence on the herbs to maintain regularity. If the product included senna, cascara sagrada, turkey rhubarb or cape aloes then this is likely the problem. The way to remedy this is with fiber and plenty of water to give suffficient bulk and help strengthen the bowel muscle. Also slant board abdominal exercises and general exercise will also help.
In the meantime, use enemas or colonics to clear everything out. And a series of colonics can also help to improve the condition of the bowel muscle.