Constipation concern

So my 15 month old daughter poops every day(sometimes multiple times), however when she poops she grunts a lot and it’s harder poops...I’ve been in contact with my dr trying different things and have tried so many things as far as different foods, water, apple juice, prunes, even prune juice(thank goodness she loves prunes), she gets yogurt daily, etc. nothing seems to help. She still has to grunt to get it out..has anyone experienced this and found something to help?