Final answer:
The child's symptoms point towards a diagnosis of sickle cell anemia, with a likely complication of osteomyelitis or bone infarction causing the femoral point tenderness, fever, and malaise.
Step-by-step explanation:
The question suggests a child with point tenderness on the femur, fever, and malaise, asking for a diagnosis and the most common cause. Given the provided symptoms and the specific demographic information about the child, the diagnosis to consider is sickle cell anemia with a possible complication of a vaso-occlusive crisis leading to osteomyelitis or bone infarction, which are common in African American or Mediterranean populations due to higher prevalence of sickle cell trait and disease. The fever and point tenderness suggest an acute condition, possibly infection, with osteomyelitis being the most common cause of bone infection in patients with sickle cell anemia.