If this happens a few hours after eating something, then that something you ate or drank is the most likely cause. Any number of natural or processed foods can cause an intolerance, either mild or excruciating, depending on your body's reaction to it. Everyone's different.
If it's mild, most people just go on consuming the problem food, not realizing the damage its doing to their immune system. Coffee or chocolate can be problematic for many people without them realizing it. Broccoli is also a bloat-inducing food for some. Anything with wheat in it is not assimilated all that well by the digestive system. Sugar is by far the worst thing you can eat, so eliminating that..especially artificial sweeteners goes a long way to promoting good health.
The solution of course, is to pay attention to what your body is telling you, and eliminate such foods from your diet.