I hate to be so graphic, but I was once told that if your stools (D) have what looks like an oil slick on top( like happens with me on a really bad day ) that it could be a sign of some parasite. I have had my stools checked for parasites twice in a year and each time, negative, but is it possible that these tests don't cover all parasites?After a bout of this type of D my stomach feels perfectly clear.. as if I've come to the end of the line.. at least for that day. This is so embarassing but had anyone else experienced this?Thanks, Libbys