B.C.
Our pediatrician once told us that once a gut is irritated it can stay irritated for a long time after the initial source of irritation has resolved itself.
Our son had diarrhea that lasted about 8 weeks.
No fever, no sickness, just the runs for the longest time.
He just had very irritated bowels.
It gave him a wicked diaper rash (he was 18 months).
As long as you keep them hydrated (and electrolytes balanced), they do alright.
Give her intestines a break, put her on clear liquids
Pedialyte, Gatorade, soup broth, jello.
People can go a long time without eating solid food, so don't worry about it.
Stay away from dairy and sugary drinks - they seem to help keep the irritation going.
Very slowly (after a week or two), start up on the Bananas, Rice, Applesauce and Toast (crackers will do).
Work in just a little yogurt - like a spoonful.
Be careful with it because probiotics can give some people diarrhea and she's already got that.
Then add one thing back at a time (and stop and go back a step if the diarrhea comes back) - mashed sweet potatoes, potatoes, soft boiled eggs, etc until she's back to normal.
It can take a long time, but you will get through it.