Suggest Treatment For Constipation In A Child

Baby (10 month , weigh 9.3kg) has constipstion past 15 to 20 days. He has dry stool and making to much effort. We have given syrup duphalac from abbott as suggested by doctor. But it helps only once we give after that the situation becomes same. We give him smashed apple and banana Similac(gain), cyralic(fruit, wheat, rice ) . Kindly suggest what can be done.