Is hard poop a good sign? What is the best but affordable milk for 3 months infant and up?

My daughter is turning 3 months old this coming 15th and we recently switched milk a week ago from Lactum to Nestogen. Based on observation her poo is now harder than before. I'm concerned if this is going to be ok since my daughter is having a hard time getting it out. Is hard poo a good sign of digestion? Please share if you have ideas. Thanks in advance. #pleasehelp #advicepls #firstbaby #1sttimedad