Hello and thank you for posting your medical question on E health forum.
Stomach or intestinal gas is a byproduct generated during the process of digestion. It is generally expelled from the body, either through the mouth (called belching or burping) or through the rectum (flatulence or flatus).
The flatus if smells bad, is due to fermentation process of the colon contents, which generates sulphur gases, which produces that foul odor. This could be due to indigestion or reduced quantity of good bacteria in the gut.
In addition to dietary and lifestyle changes, OTC medications such as activated charcoal, probiotics and digestive enzyme supplements can be used for intestinal or stomach gas relief.
Activated charcoal tablets have the best effect in relieving your symptoms.
I hope you find this helpful.