A 5-year old child developed seizures a few months ago. The seizures sta with feeling of strange smell (burning rubber), continue with generalized contractions, and end with rhythmic spasms. Consciousness is lost during attacks and the child is confused afterwards. When the seizures staed, the child was referred to a neurologist who prescribed phenytoin as the initial treatment. Now, the parents bring the child back for scheduled DTP immunization (diphtheria, tetanus, peussis). Which of the following is the most appropriate next step in the management?