It sounds like you have eaten something that is extremely acidic or spicy that has caused hyperacidity in your system. Usually hyperacidity is neutralized in the body before food reaches the small intestines for absorption; however, if this is not adequate the acid or the food itself might have destroyed bacterial populations in the stomach.
Acid is secreted in the stomach by the parietal cells. These cells are susceptible to being stimulated and hyperstimulated by certain types of foods like heavily spiced foods, junk food, and certain kind of drugs and analgesics. Acid is required to digest food normally and the enzyme pepsin also requires an acidic medium to work. If there is too much acid in the stomach, the characteristic belching occurs and foul belching is usually an indication of what you have eaten. In odd cases, like in the case of a disease called Achalasia, the belching is especially foul due to food fermenting in the food pipe. However, this should not be a cause of worry if you are able to swallow properly. If your esophageal sphincter refuses to let the gases from the stomach to be released, you end up with bloating. This is simple to cure and an antacid or swallowing of liquid will force the gases out – though sometimes uncontrollably. Once the food is ready to exit the stomach and proceed to further processing, the acid in the food is neutralized by a substance called bile secreted by the gall bladder. If acid is not neutralized or the bile quantity is too low, as is the case when you have liver damage or gallstones, the acidic food cannot be worked upon by further enzymes and the intestinal bacteria that would work on the food would be killed by the acidity. To ensure that bile is secreted in normal quantities, consume a few spoons of honey regularly as this stimulates bile production.
One of the cause for diarrhea is low quantities of digestive bacteria in the gut. The balance of digestive bacteria and more harmful strains is usually challenged by intestinal infections, antibiotics, and acidity. To return the balance to the intestine, start your day by consuming probiotic yogurt until your stomach can withstand proper food. Remember to also constantly drink water and ensure that acid levels in the stomach are kept low. Also, try to give your system a rest by fasting for a day and only eating fruits.