My granddaughter was born at 3lb 8oz, 5 weeks early....she is now 9, started having yellowish tinge to her eyes a few months ago, from when she was little she has had problems moving her bowels...had a stomach X-ray done recently and they said she was backed up....also had her school physical and blood work showed elevated bilirubin, repeated test, still elevated....liver enzymes normal....what can be the cause...