XP: Help with PT regression! *UPDATED*

Two weeks ago, when I picked DD up from school, her teacher told me that DD peed on the potty and had to poop but wanted to go at home. The rest of that day, she complained about having to go but didn't go until after dinner. Over the next week, DD (who has been PTed since January and usually poops daily) would spend the day whining and crying and screaming that her bottom hurt but refusing to go on the toilet; she ended up going in her pants three times and on the toilet only once, all while screaming that it hurt. I kept telling her that the only thing that would make her feel better was to go poop, gave her pear juice and cut back dairy, and even offered various treats, but she would just cry and scream and tell me she didn't want to go.

Finally, last Tuesday, after it had been going on for a week, I called the pediatrician who suggested giving her Miralax. Well, that same day, my mom happened to be coming over and brought a prize, and for some reason that worked, and DD went with her as soon as she got to our house. The next day was my mom's day to watch her while I went to work; DD said she would go poopy at Mimi's house, but ended up having to go just before we were ready to leave. She cried while she went but admitted she felt much better afterwards.

Because she went those two days, I held off on the Miralax, thinking maybe she had gotten over it, but then she had another rough two days, so we've been giving it to her every day since Friday. Still, Friday and Saturday, it was like she was PTing all over again, because I saw her get the I'm-about-to-go-right-now look in her face and rushed her to the toilet before she went. She didn't go yesterday, and now today is starting off with the same complaining about her bottom.

It seems like holding it in at school may have made her constipated (although the poops she has had haven't seemed hard or anything), and then the pressure on her bottom made her sore which in turn made her scared to go poop. Since she's never been constipated in her life, it seems like it's all in her head, whether it's a reaction to starting school (or just not wanting to poop there), a delayed reaction to her baby sister, or missing Daddy (who had left for a week-long trip the day before this all started) -- or probably a combination of those three things.

Anyway, that's where we are now, and it is so frustrating to me to have to deal with her spending the entire day crying, and it's upsetting to both of us because it's so obviously painful for her. I am seriously at my wits' end. I just want my happy little girl back.

If you've made it through all this, I would so appreciate any advice!

UPDATE 10/25/10: The regression seems to have ended! The last time she fought it was Wednesday, and since then, she's been back to her normal pooping habits. I'm not sure if it was just a phase, or if she really did need the help from the Miralax to get past it (we used it from Friday to Friday), but she's back to going by herself without any complaints. Yay!