My DD recently went through this. I know she has a good diet and eats and drinks well. We tried switching her to normal milk (she is lactose intolerant) hoping it would help empty her bowels but to no avail. What worked for us (the liquid parafin assisted but didn't REALLY help) was a microlax. It is an enema which is bought over the counter. You insert half the applicator tip into the rectum, empty the contents into the bowel... and wait. You usually get a result within 15 minutes. I had to give DD one 2 nights in a row and then after that she has been fine - she just needed a little help to clear the back log.
Before anyone runs out to purchase microlax - please keep in mind I am a Registered Nurse and have no drama in administering this to my own child. However, if you are interested in going down that path please discuss it with your local pharmacist first. There is an age limit (I think 2 years of age?) and it can be a little uncomfortable for them. It produces mild cramping in their abdomen. It is much gentler than a FLEET enema. This kind of treatment is not up everyone's alley - it can take a bit to get over the mental barrier of inserting something into your own child's rectum.
In relation to too much fibre - it is not so much the quantity of fibre but not consuming enough water to match the amount of fibre being consumed.
HTH
MG

