What is her fluid intake like? If she is still drinking jsut keep the fluids going and keep trying with the food, let her pick at it until she regains her appetite. A trip to the Dr would be good as well if she hasn't improved. But if she stops drinking and starts showing signs of dehydration I would get her checked sooner rather than holding off.

When DD1 has been sick she drops food pretty quickly, but we can get some fluids into her except for about 12 months ago, where we tried for nearly 3 days and hardly got anything into her, and ended up dehydrated

Take care and I hope little Miss is feeling a lot better very soon xxoo