when I nursed my son during pregnancy with my second son, he got a BAD case of colostrum diarrhea from about 30 weeks onwards. It was yucky but not harmful.
It may be that you are producing colostrum now and that is setting her off.
Or alternatively, do you know whether you still have milk? Mine dried up at 24 weeks or so but most moms I have talked to have lost their milk entirely by 16 - 18 wks. It could be that she is still nursing but without your milk so something else might be upsetting her tummy without your antibodies to keep things calm.
Just some thoughts.
You know the attributes for a great adult? Initiative, creativity, intellectual curiosity? They make for a helluva kid...