Hey, I had DS on Nan as well, and for some reason it would make it really hard for him to poo, and he would scream, scrunch up his face, raise his legs, all whilst trying to get the damn stuff out... So I switched to S26 Gold and he never did it again. I also had him on Infacol for wind too cos he wasn't a very good burper, and he drank his bottles really quick.

I'm not saying thats what it is for sure though, just that Nan wasn't suitable for mine

Good luck!!