I do not know the age of your grandson. But if he is able to gulp the following herbal powder mixture, pl give to him. BAEL pulp dried powder, Dry ginger powder, Isabgul husk - all 1:1:1 ratio. This mixture should be given 1 tsp thrice a day. Morning and evening mixed in yogurt and night mixed in honey or direct with lukewarm water. See for a day or two. If yogurt also does not suit, then all the three times give with honey. This ayurvedic mixture is safe, no side effects, no interaction with other medicines. This combo is Deepan, paachan and shodhan i.e. appetite flaring, digestive and Bowel cleanser. Hope in less than four weeks your grandson will show improvement.