I have a question...my baby girl is going to be 6 months on Wednesday. She's been constipated with…

I have a question...my baby girl is going to be 6 months on Wednesday. She's been constipated with hard stool off and on for the last month. What can I give her to help this? She's mostly formula fed now, but I pump and give her what I can, which is only an ounce at this point. Any help would be appreciated! Thanks! 😊