Warning-poop talk - Baby has hard poop

So my son is almost 8 months now. He doesn’t always have hard poops, but I would say more of them are hard then normal. When I say hard, I mean like little balls of hard poop. Like hard to squish sometimes. There has been one instance where he was backed up and pooped out a very large rock hard poop. He was screaming to get it out. I honestly thought I was going to have to bring him in. I have communicated this to his doctor a few times and she suggested apple juice every now and then to help. Sometimes it does , sometimes not. He has had prunes also and that doesn’t seem to make a difference.. I have also tried just giving him a little bit of water. anyone else go through this? Any suggestions? I’m going to bring it up again at his next appointment but thought I would reach out to other people too. Sometimes it seems really uncomfortable for him. 😟