What Causes Fever,headache And Vomiting In A Child?

My daughter threw up early this morning (4am-5:30) two seperate times. She has a low grade fever, and complaining of a really bad headache for over 24 hours- what could this be? Normally, when she has a virus she doesn t complain of her head hurting this bad and she has had strep throat enough times to tell me if she thinks that is it. She is not complaining of her throat hurting. She is 9 years old. Please give me some feedback. Thanks