Bad breath can be a common sign of a deficiency in beneficial gut flora - otherwise known as probiotic bacteria strains. This is normally caused by exposure to antibiotics - either directly or indirectly via breastmilk. The antibiotics cannot discriminate between good and bad bacteria and effectively kill both, leaving you a little defenceless in the digestive region.
I would suggest getting an infant probiotic from your local health food store (you can buy it in powder form and add it to her milk or water etc).

Hope this helps.

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