I think relaxation could definitely be the reason. I'm usually home with kids, but if I have several days where I'm running around, I don't "go". Then I have a day home and I go and go and go (although I don't have diarrhea).
Is there anything you're eating that could still be causing the diarrhea? Dairy? Any sometimes food you're eating too much of? I'm not savvy enough to know if you're percentages are good. Maybe someone else can give you better info on that.