You should stop giving Meftagesic and consult a pediatrician immediately. Using this combination medication (paracetamol and mefenamic acid) for more than three days without medical supervision is not recommended, as prolonged use can increase the risk of stomach irritation and kidney strain. Additionally, a fever persisting for three days requires a proper medical evaluation by a doctor to identify and treat the underlying infection, rather than just continuing to suppress the fever. Please do not switch to another medication without professional guidance.