SUPER runny diaper normal?

Emily

My son had 4 diapers like this yesterday, each more runny than the last. He also had this diaper this morning. I’ve been putting little amounts of prune juice in his bottles (per recommendation of my public health nurse) because he was mildly constipated when he started rice cereal. I’m going to stop doing that but I’m wondering if this means he is sick? Thanks in advance!