Formula Not Working

Okay momma's my baby has been on 4 types of formula since he's been born.

He's currently on soy. The one he was on before this was nutramigen. It was going great for a while with nutramigen but the moment he had a slight problem ( diarrhea for like 2 days ), they took him off and switched him to soy.

Now he screams every poop and I have to help him push out. This morning was the last straw. When it feels like I'm pushing out a rock and it's making him bleed when he pushes on his own, obviously it's not right.

Doc tells me to give him pear juice to help his poops. I shouldn't have to give him juice on top of his formula to be comfortable.

Any advice ?? He just went in Tuesday for an appointment and the same thing was said to me about juice. 🙄