Mummies how much milk should a 6 mth baby drink? How much water? Recently baby screams and arches back while crying, is that normal?

Arching back accompanied with crying may mean that your baby is having reflux. It is also common for babies to arch their backs to indicate that they have had enough to drink and want to move away from the breast. You can try changing the position of your baby to help him/her get into a more comfortable position when he/she arches his/her back. Hope this helps! :)