Toddler and miralax

My 2 year old daughter has been having a hard time pooping a lot recently. She complains her “bum hurts” almost daily. I have had to give her a baby enema after 3 days with no poop at one point. When she does poop, it’s a small amount and hard. I know it’s from her eating. She typically eats tons of fruits and veggies but lately all she wants is pasta with sauce and yogurt. She’ll eat a couple fruits a day and maybe one veggie. She will not drink prune juice not matter what I put it into I got her miralax and it’s like she KNOWS it in her drink. I’ve put a small amount in her drinks (and I can’t taste it), but she’ll refuse to drink them. Any suggestions?