Hit Head. Having Headache, Body Ache And Stomach Ache. No Memory Loss, Dizziness Or Disorientation. Minor Concussion?
No, it definitely doesnt sound like serious head injury,contusion or commotion. Also it cant be caused by such mechanism (ball hit). If she didnt experience dizziness, blackout, amnesia, vomiting as you said I really think there is no need to worry. SOme other signs which can indicate head and neck injury are tingling sensation in neck and hands, drowse, vision and hearing disorders and concentration loss so ask her about it.
It sounds to me like typical gastroenteritis, viral probably. All you need is give her enough fluids to prevent dehydration and easier food such as fruit, vegetables,soups and soft-grain products. It should pass in 2-5 days and if symptoms persist after this you should visit doctor.
WIsh you good health. If you have any question I ll be glad to help