A. Diarrhea from a simple stomach virus can normally last a good two weeks, but since it is lasting longer than that and getting worse, a recheck by her doctor would be a good idea.
An infection as a cause for the diarrhea is still a possibility, especially if anyone else is sick with the same symptoms.
If no one else is sick, it is also possible that the diarrhea is being caused by an intolerance to something she is eating, or if she is breastfeeding, something that mom is eating.
Have you started solid foods already?
Does she drink juice?
Do you have any reptiles in the house, like a turtle, which can be a source for Salmonella infections.
If she is drinking formula, persistent diarrhea could be a sign of a formula intolerance or allergy, even if she had been doing well on the same formula for a while.
