did your PD prescribe you probiotics? if baby is still on BM, you can give him Vivomixx as it contains probiotics + vit D. https://s.shopee.sg/1Viuya2Inp if baby is majority on FM, then you can add Kindernurture probiotics into his milk. https://s.shopee.sg/AA0tIdAPSz
Give more porridge water instead of formula until the poo stabilised. Need to sooth the stomach first, if not all drink intake will came out watery and baby will suffer.
Change to soy milk powder until diarrhoea stop.