Some viral infections can lead to inflammation in the joints or muscles, which may result in limping. For example, viral infections like coxsackievirus (hand, foot, and mouth disease) or influenza (flu) can sometimes cause myositis (muscle inflammation) or reactive arthritis, which may present with joint pain and difficulty walking. If your child has a viral illness and develops limping, it's advisable to consult a doctor for assessment and appropriate management.