Good day. Ladies, who are on IV feeding, we've been doing it for a mon…

Good day. Ladies, who are on IV feeding, we've been doing it for a month now, since delivery, we were eating Nutrilon, didn't poop and burped, had stomach pain. Pediatrician advised us to let the baby try breast milk, switched over. In the end, we didn't gain weight, only 300g and everything was wasted. We switched to formula after a week and completely on the formula for 4 days. When can we switch to another formula? Who is using what? I don't trust the mediator anymore, of course we will change. She said to observe for another week and then think... but the baby cries all day and night ?