A 4-year-old boy is brought to the emergency department by his parents for evaluation of sore throat and cough. He is unusually quiet and withdrawn and frequently looks to his father before responding to questions. Physical examination reveals bruises in various stages of healing over the buttocks and back. A rapid antigen detection test is positive for streptococcal pharyngitis. Chest radiograph (Figure A) demonstrates rib fractures. The father states that the bruises are from rough play with the boy’s twin brother and that the rib fractures occurred when the child fell off a tricycle. Which of the following is the most appropriate next step in management?