Anal Retentive toddler

I have a 3 year old daughter who is refusing to have a bowel movement.  
We started potty training at the age of 2, at her own pace. We got pretty successful around 30 months. She then got a double ear infection and was put on some strong antibiotics. This put us back at square one.
Ever since she crosses her legs and holds it in as long as she can. If we put her on the potty she just cries and says she doesn't want to go. Every now and then we will get a "skid mark", some she just can't hold in. Other than that she refuses to go.
She takes Miralax every day, and fiber vitamins everyday. It doesn't do anything. Also I have started giving her activia and that also has not made a difference.
I have tried talking it over with the pediatrician and all she says is to stick with the Miralax she will eventually go. It has been to long and I am starting to worry, plus school starts soon and I don't know if they will put up with it so I would like to have some sort of a game plan.
PLEASE  HELP!!!

[Kevin Kennedy, Ph.D.]

I agree with the pediatrician's guidance. She is only three - there's no rush. In fact, if you become overly invested in her accomplishing toilet training, you will exacerbate the problem. Be patient and supportive, using a reward system to help motivate her. Employ children's stories and DVD/video as well.