Sounds to me like what I experience when I eat oranges. It isn't like diahria it is just as if it is not solidly digested.
A holistic doctor told me this was symptomatic of a food allergy . It is your bodies way of getting an offending substance out of you as quickly as possible; even before thorough digestion.
You might want to consider if you may have a particular food that you eat alot of that you are somewhat allergic too. It could even be one of your favorite foods and one to which you show no other outward or inward symptoms as this is exactly my experience with oranges.