My son is 4 months old and was suffering with lactose intolerance problem from 3rd month and am feeding him with zerolac instead of his regular lactogen. Today l have used lactogen to check as he was healthy now but as soon as I gave him lactogen the problem raised again and he has continuous watery motions and vomiting from morning. His pediatrician said to use the same zerolac for him continuously and never use other milks. Please give me some suggestions regarding his condition.