In the event of an emergency, do not worry about insurance issues and just head directly to the nearest emergency room.
Use the general emergency number 107 if you need an ambulance.
Several hospitals in Argentina have English speaking staff at hand. Especially in Buenos Aires this will be the case. In Buenos Aires the Hospital Británico (private hospital) and the Hospital de Niños Dr Ricardo Gutiérrez (public hospital) are the places most likely to have English speaking staff.