L.S.
The biggest indication to ME of how sick my kids are is how they're acting. If my child is lethargic and doesn't want to move off the couch, then they're *sick*. If they're playing like normal, but having some "issues", then I just treat the symptoms and it's always passed in a few days.
I'd recommend the BRATT diet for your daughter until her bm's go back to normal. That's Bananas, Rice, Applesauce, Tea and Toast. Make sure the rice and toast are white (easier to digest because they're not "whole") and don't add anything to them like soya sauce, butter, etc. I will add a tiny smear of peanut butter to my kid's toast, but that's just so it's not SUPER hard. Also, make sure she's getting plenty of fluids. I give mine mint tea and water....nothing acidic like apple juice though.
If she's still complaining of a tummy ache and having diarrhea, then I'd take her in by the end of the week.