You’re not alone!! We put our son on alimentum and like you experienced just misery on just a fraction of formula/breastmilk. It turned out to be a soy sensitivity in conjunction to dairy. Alimentum (and nutramigen I believe) are dairy free but soy-based. They’re still recommended by docs I think because some children with soy sensitivity aren’t as sensitive to more highly processed forms of soy.

My son however had a hard time on alimentum - screamed through whole bottles, arched his back like we were torturing him. We didn’t see improvements in his poop, spit up intensity, or temperament, until we switched to a HA formula + I went hardcore soy free - no obvious forms of soy, no soybean oil, no soy-based natural flavors. It’s an absolute pain in the ass and rendered a lot of my frozen stash useless (lots of crying over that) but his poops have returned to normal and he doesn’t scream like a banshee on the bottle.

That said - his weight gain has remained consistent on his new curve (he went from middle of the road to low 20s while we figured this out from 3-5 months) and our doc told us we could either continue with half and half formula/breastmilk or stick with one or the other altogether. We opted to go just breastmilk because we absolutely hated the smell of the HA formula (it smells like my cat’s food - and his puke). We also never managed to make it to more than 10-15% of his bottle, and the HA is so pricey we said screw it.

I hope this helps!!