The few weeks I was able to BF I was taking Zoloft as well. He didn't have any issues with it that I saw.
Maybe since you said she is doing so well on Soy, it wasn't becuase of the Zoloft, but because of something you ate everyday that didn't agree with her tummy. Like milk?? Are you a regular milk drinker? I know that can affect some babies, also spicy foods... maybe you could try cutting something out that you know you consistently eat/drink that could be the problem. If not, then just stick with the soy.
* Edit.. something just crossed my mind also.. Do you drink coffee? I had to cut out all coffee while I was BFing.. He never slept and it seemed like it made his tummy a little off.. I know coffee is a natural laxative, and some laxative only make people feel crampy.. just another thought

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