I understand your concern about your little one's diarrhea. While Econorm (Saccharomyces boulardii) is a helpful probiotic for diarrhea, taking it daily for a year is quite long. Since he is experiencing watery diarrhea specifically after drinking Zerolac, Econorm may not be solving the root cause. This reaction could suggest an underlying issue, such as a milk protein sensitivity, rather than just lactose intolerance. Please consult your pediatrician before continuing Econorm or changing his diet. They can safely evaluate his symptoms and guide you on the best next steps for his tummy. Sending gentle thoughts to your baby boy!