It's not unusual to have an odor but usually not a bad one. Foul as in notably bad can be bacteria and antibiotics are used to treat this. Diseases are not a concern. Most likely this is the natural smell and not a problem. But if the odor becomes quite strong, you can be checked at the doctor's. They simply swab the discharge and look at it under a microscope to see what it is. Then they treat it. Nothing serious! good luck