The science is still very new but there is ample anecdotal evidence that probiotics aids in many digestive problems. I have also had personal experience with it where even a single capsule of probiotics (the kind with several strains of bacteria) has helped with stomach upsets within a couple of hours. If you take anti-biotics it is also important to take a pro-biotic because the synthetic anti-biotics rids our gut of a both good and bad bacteria. NOTE: What probiotics are not useful for is in aiding bowel movements when you have constipation.
Below is a video that explains what we know and do now know about probiotics: