My baby boy is of 3 months old. While feeding, i observed that he shows interest to suck from only one of the breast. When I forcely tried to feed from another breast, sometimes he takes but often he feels like vomitted. My mother said that if I don't feed and clear the breast milk from both the sides, it becomes soar to baby. How true is it? Any suggestions to make my baby feed from the other side would also be helpful