My 2 Yr Old Step Daughter Has Problems Pooing (she

My 2 yr old step daughter has problems pooing (she has done for months) when she does poo she screams when we wipe her but my maim concern is that she screams when we try to wipe her front on the 2 occasions we have manged there has been a yellow whitish discharge on the wipe and there has been blood aswell I have told the mother but she justified the doc said the blood had 'traveled' from her bum to her front I am very concerned on a couple of levels