Stomach Virus?!?

Has anyone's LO had/have a stomach bug? My daughter started having diarrhea last weekend which caused a really bad diaper rash.

We took her to Urgent Care on Tuesday but there wasn't much they can do. She's had no fever, is still eating the same amount of formula if not more and is not lethargic. She seems happy for the most part but is def. more cranky than usual. I just feel terrible because her diaper rash has gotten so bad. They gave us a cream for it but it doesn't seem to be working too well since she keeps pooping.

We're bringing her to the doctor tomorrow. I want to make sure it's not anything else. Has anyone gone through this and how long did it last?