Hi thanks for asking question. Noted your friends child diagnosed with nephrotic syndrome.. So if it is associated with inflammation of glomerulus that is glomerulonephritis then also such symptoms do occur. And secondly yes if cough , cold , sore throat present and headache and fever might be from acute viral infection.. Treat it symptomatically. If abdominal symptoms present then abdominal diseases like hepatitis can lead headache. The steroid also can lead to headache ... I hope my answer will helpful to you... Take care...