Be very careful before you try any of the suggestions here and research it and talk to your doctor about it beforehand. If you're sure it's coming from your colon, get a colonoscopy, sometimes enema use can make you dependent on them to have a bowel movement or the irritation from the garlic which is very strong could make it even worse or make you smell of garlic. Maybe use a store bought enema once or twice and see if it helps if you're going to try that but I wouldn't suggest it. It's good to take a high potency probiotic to populate your gut and colon with good bacteria and maybe lessen the odor. The first stop is to a doctor.