Get some Pedialyte so she at least has a balanced electrolyte fluid in her stomach. If she will drink milk, give her that as well. Is there any chance they would have missed the penny?
If she didn't have a penny in her stomach, maybe what happened is that she had vomited up the penny, and now doesn't want to irritate her throat or risk vomiting again. If that's the case, try butterscotch pudding. Soothing, cool, slips down easily, and kids like it for its lovely sweet flavor.
My initial thought is that she is afraid to eat because of the diarrhea she had a few days ago. Was it painful for her?
I would take it slow with her. So long as she is drinking, that is what is most necessary right now. Perhaps bribe her with just a little bit of her favorite food. Also, ask her why she is afraid to eat and talk to her about it. It may help.