my baby is 3 month old n I use to give her lactogen stage 1 n with that she has gas problem can I be shift to nan Pro

don't change by urself..
consult the doc first..

Gas issues arise due to use of bottle. Make sure you burp your baby after every couple of ounces and after a feed hold the baby in an upright position for a few minutes

Also you may try using anti-colic bottles. They do help