hello,thank you for the consultation,you din t mentioned the age of your baby?your history is not much informative like you dnt tell about any other symptoms as loose stools,vomiting etc.so after all i will suggest you to try to make him drink more fluids in any form like water,juices,milk (isomil milk as you told),ors fluid etc otherwise he may develop sever dehydration.so you have prevent dehydration and consult the pediatrician if still he doesn t drink any thing.he may need admission .wish your child good health.