We need help

So my fiancè had some Mexican food last Friday. Ever since then, it’s been horrible. Saturday she started having diarrhea. She can’t keep anything down. Everytime she eats, literally secs later it comes out. She hasn’t thrown up at all. One night she had a fever. Went to urgent care a few days ago. They said stomach flu. But myself and my daughter haven’t caught it thank God. But now it’s almost a week and she still can’t keep down anything except maybe some crackers. She tried a chicken wrap yesterday and it was clear that her stomach did not digest the lettuce. She’s just sooo hungry and wants to eat but it tired of sitting on the toilet. Oh and btw she did have Imodium and it didn’t work 😩