Suggest Treatment For Chicken Pox

My 7 month old baby boy have developed red spots a day before. yesterday a small blister like came . paediatrician told with 1 blister its not possible to say that its chicken pox. but today that blister became more big and there are other blisters on his genitals , lower abdomen , head and hands. its confirmed now that he has chicken pox. what medicines are recommended , and what type of foods we can give it to him . from past 3 weeks we are giving him antihistamine for coughing as he developed croup before . can we still continue to give him nan.