Tests were unnecessary before 5-7 days of continuous fever. Most likely to be viral fever and usually last up-to 3-7 days,specially if not accompanied by any other symptoms. Stop all meds,just give paracetamol every4 hours if required. If not improving in 2-3 days time OR accompanied by other symptoms like vomiting and diarrhea or coughing,consult your paediatrician again. Ensure a healthy diet and extra fluid intake.