Hi and thanks for the query, In a young girl as such, a few questions must be addressed carefully. Considering her age, with due respect to the fact that she does not like playing, however, the commonest cause of the pain should be traumatic. If not a fall or being hit, her sleeping position too could be a contributing factor. Presence or absence of fever, changes in appetite are careful considerations to be taken. Putting her on simple analgesics of non steroidal anti inflammatory drugs might give relief. However, if symptoms persist, blood tests to evaluate the white blood cell count and acute phase reactants to exclude an osteomyelitis or bone infection might be necessary. At the extreme, X rays might be needed at some point. I suggest usage of simple oral analgesics and local non steroidal anti inflammatory drugs for now. Persistence of symptoms should warrant consulting her primary care physician. Thanks and best regards, Luchuo, MD.