According to your description you are probably experiencing constipation. It seems obvious that after several days without any bowel movement larger amount of gases will be collected in the large intestines. Those gases are the result of bacterial metabolism in the large intestines. Sulfurous or a sulfur-like smell is in fact smell of H2S-gas that originates from amino-acids metabolized by the intestinal bacteria.

Constipation is only a symptom, not a disease. If there aren't any organic reasons present for the constipation, such as tumors, it could be symptom of a functional disorder called "Irritable bowel syndrome (IBS)". Constipation is treated with a fiber diet (food that contains a lot of cellulose fibers), paraffin liquid, ricinus oil, alcalax…