What Causes Yellow Orange Pigmentation Of Skin?

my 5 year old daughter is waking up with a yellow orange tinge to her skin with the darkest coloring in her feet and lightest coloring in her face. By the time she is dresses, fed, and ready for school the condition is mostly cleared up. when she comes home from school any indication of the skin coloring is gone. this has been occurring for several months despite diet changes and monitoring for possible external causes( such as dies in her clothing and shoes). She is going to her pediatrician for the second time on the subject tomorrow. Do you have any ideas that I could suggest to her doctor?