My baby is 5 months old. When he was 4 months old, I bought lactozen formula milk to feed him, thinking that only my milk is not sufficient for him. But my baby did not even drink formula milk. Every time spewed and cried a lot. I kept the formula milk in an air tight container. So after 1 and half month can I try to give the same formula milk which is an open packet Or Should I buy a new packet? it is safe to feed the same opened formula milk after 45 days gap to my baby or not?