Milk options.

Alright mamas, I did 2 oz of lactaid with 6oz of formula (nutramigen) for my son since Monday and he has been miserable the last few days. Poop has been weird. Just before his poop had mucus in it. I looked into pea protein milk awhile ago but tried lactaid before it and I’m so regretting it now. This seems like the next best option to try. Anyone else trying plant based milks? What about oat? His doctor pushed for me to try lactaid but not working out.