Prune juice for constipation

Becca • One in heaven 💛 10/14/17, and one beautiful 🌈 girl born 10/3/18

Sooo my baby is 6 months old and her doctor suggested a bit of prune juice with water to help her constipation (she goes, it’s just quite hard). I tried today and she makes faces at it. I looked up other ways to give prune juice online and it suggested in a bottle with breast milk. Wouldn’t that curdle?? Any of you tried that before?