Thanks for the query
In case of diarrhea
breast milk which contains lactose can be substituted by Soy milk( lactose free) for few days, as diarrhea causes temporary lactase enzyme deficiency. As baby recovers from diarrhea there is enough enzyme production to digest lactose in breast milk.
There are few soy baby formulas include:
Similac Isomil Advance
Nusobee soy formula( Wockhardt)
Nestle Good Start Supreme DHA
& ARA Soy
Parent's Choice Soy Infant Formula
DHA & ARA (Wal-Mart brand baby formula)
Bright Beginnings Soy Baby Formula (store-brand baby formula)
Earth's Best Organic Soy Infant Formula With DHA & ARA
You can use any one of these.
I hope this answers your query well
Wish you and your family good health