Baby constipation

Mama

I’m not sure what I can do to help. I’m starting to think our generic formula is causing baby to be constipated… am I crazy? Or is anyone else dealing with this same thing? He used to poop several times a day and now for weeks he just will not go without some kind of assistance. His poop is almost solid and he is just suffering. I started him on probiotics and they have done nothing (not even helping with his spit up/possible reflux)