Having frequent, smelly gas but not being able to pass stool can have both common (physiological) and medical (pathological) causes. Common Causes: This can happen if you eat a lot of foods that tend to produce gas, like onions or beans, if you swallow too much air while eating, or if your diet is high in sweets and greasy foods. A lack of physical activity can also lead to more gas in your intestines, causing smelly farts and constipation. For people in this situation, there’s no need to worry too much. Cutting back on gas-producing foods, being mindful not to... Learn more