The cardiologist said her heart was perfect. (YEAH!!) They did an EKG and an echocardiogram (which she slept through).
He encouraged me to continue searching for the answer because the "color change is too impressive to ignore" and recommended pursuing a consult with a pediatric dermatologist. He has a theory that she has hemangiomas under her skin that may be obstructing blood flow. He stressed that it was just a theory as it isn't his field of expertise, but that because she has noticeable birthmarks in three different areas (her nose and forehead, the top of her head, and and the nape of her neck) it usually indicates that there are more under the skin that we cannot see. Most are benign he said, but some do require medical attention. He said that it could be very possible that she has on obstructing an artery or something. He sent a letter to the pediatrician recommending a pediatric dermatologist.
So, now we will wait and see again : ) We are thrilled, thrilled, thrilled to know that her heart is okay. Thank you for your prayers. I will keep you posted.