A 18-month-old boy is brought to the pediatric clinic by his mother for a routine developmental assessment. On examination, the child can walk independently, say 10–15 words, and follow simple one-step commands. However, the mother reports that he does not point to objects of interest, does not engage in pretend play, and shows minimal interest in other children. He makes poor eye contact and becomes distressed with changes in routine. What is the most appropriate next step in management?