Whenever an infant, incompetent person or incarcerated convict has a duly qualified representative, such as a guardian, curator, committee or other like fiduciary, such representative may sue or defend on behalf of the infant, incompetent person or convict. If a person under any disability does not have a duly qualified representative he may sue by his next friend. The magistrate shall appoint some suitable person who shall not be required to be an attorney-at-law as guardian ad litem for an infant, incompetent person or incarcerated convict not otherwise represented in an action.