Constipation vs holding it in willingly


So daughter is almost two.

We have constipation about three or four months ago but fixed some things and was back to normal after a day or two. Then a few weeks after the constipation is gone she is acting like it is bothering her again but what she passes is normal BMs. So this last week we’ve been taking her to the potty whenever she acts this way and I’ve noticed that as soon as she feels it she stands up and clutches her little cheeks together and refuses to go... she will take all day to go and when she does it is half hard half normal. Just wondering how to get the kiddo to stop holding it in and just let it go. I don’t know how to help her relax when going potty. Today her daddy is telling me she won’t eat and is fighting going to the potty again. Starting to get worried a bit so bringing out the prunes/prune juice again and if it’s still bothering her tomorrow night gonna call pediatrician but I wanted to see if any other moms had experience to share/advice before that.