Is anybody dealing with poop issues with their babies?

My LO's poop schedule kind of changed about 3/4 weeks ago. She use to go every day....then stopped going. I wasn't too concerned BC I was told they may poop less as they get older and going a few days without one is okay. I only became concern when she did go 2 days later and it came out like a hard dry chunk. So after about a week an a half of her not going for a day or two then it coming out quite solid and dry looking we went to the doc.

The doc told me to add 4 oz a day of prune juice. I only did 2oz and she went....a crazy amount...and then had runney poops. (So I knew 4oz was def out of the question!!)

I continued with 2 oz for a bit but backed off to 1 oz a day BC she would poop a solid one (like dog poop) followed by diaherra. I don't want her to have diaherra!!

Also I believe the prune juice is giving her bad gas/cramps sometimes as she will scream bloody murder sometimes then have a blowout .

The problem is is she won't poop without it and gets uncomfortable. Like its not a 1 time constipation thing....its ongoing it seems. And even with the juice she will produce a solid like poop. Today I only gave her .5 oz.

Any ideas or other recommendations easier on the tummy ? We go to the doc wed the 12th for her 4 month so it will be discussed there.

Thanks!