Hi, Any child with vomiting and headache should be treated seriously especially after exposure to infection - water and environment. I suggest the best way to deal with it is to take him to a local hospital (EMERGENCY) to rule out severe throat infection, ear infection or even pneumonia or meningititis which is an emergency. DOCTORS there would do a complete physical examination and order urine test, blood test, throat swab, CXR etc., to confirm diagnosis before instituting measures and medication whether IV or oral, based on their discretion. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Law, General & Family Physician