If your 3-month-old baby is constipated, there are a few non-pharmacological measures you can try to help. It's important to determine what constipation means for your baby, as it can vary from person to person. Generally, infrequent, irregular, difficult, painful, or incomplete passage of hard stools is considered constipation. If your baby is experiencing symptoms such as a family history of Hirschsprung's disease, thyroid problems, delayed growth, ribbon-like stools, blood-tinged or black stools, fever, vomiting, abdominal distension, anal fistula, extremely painful bowel movements, or constant and uncontrollable crying, it is advisable to consult a doctor. Ensure that the milk is diluted with the correct amount of water as recommended by the manufacturer, and encourage your baby to drink enough. You can also try helping your baby with bowel movements by gently moving his legs in a cycling motion. If these measures are not effective, there are over-the-counter medications that may help, so speaking with a pharmacist or visiting a pharmacy would be beneficial.