Had an interesting case several years ago. The mothers
husband was not breastfed because of projectile vomiting
after breastfeeding and three of her children were not
breastfed for the same reason. With the fourth baby I
suggested that the mother eliminate all  milk products
from her diet and it worked. She was so happy she
nursed for a long time.  Her oldest daughter had a baby
recently and this baby also was projectile vomiting
after every feeding until Mom eliminated milk products.
Happily it worked for her also. No more soy in that family!
Ruth Bacon  IBCLC  Ontario