Hi.. Welcome to healthcare magic.. According to your complain you have problem of foul smell at bowel movement that may be because of gas problem.... If this problem is long standing than barium x abdominal x ray helpful in diagnosis.. Simethicon drug can use for gas relief.. Stool examination test is helpful to check infection present or not... Drink more water.. Avoid gaseous foods like cabbage, cauliflower, turnips, carbonated drinks etc... Consult a gastroenterologist for further diagnosis.. I hope my guidance helpful to you... Take care.. Thank you.