Dd (just turned 2) has always tended towards being constipated but for the last few months I think has been holding poo in when she needs to go. She will go somewhere private, and stand kind of 'banana shaped' with bum clenched and hips pushed to one side, whimpering. She will do this intermittently for up to 4 days, getting more and more withdrawn and miserable until eventually a ginormous poo comes out, then will be happy and carefree for the next day or two til the cycle starts again.
She's on lactulose but it's got less effective and still goes a few days between poos. We make her drink several small cups of water a day, as recommended by the doctor. She eats lots of fruits and has a pretty good balanced diet really.
She also gets stressed when her nappy's wet and wants it changed straight away - but point blank refuses to try sitting on the potty or toilet. I hate seeing her lose so much time when she could be playing and learning to worrying about poo... But don't know what to do to help.