If Chelsea is totally FF, and its been over two days she might be constipated. DS does this too, and I find that extra water, pears and holding him in a sitting position with his knees up (like a squat, but I am holding him on my lap) can usually get things going.
As Madeleine says, prune juice can be really harsh (not sure about the baby prune juice, I know I've seen "apple and prune' baby juice ) But maybe a teaspoon of actual stewed prunes - you can get SPC canned prunes.
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