D..
S., I'm so sorry that the first poster to your query here is by a crappy robo spammer. It will disappear in a few hours.
I'm so very sorry about your son. My own children didn't have this issue, but a friend of mine's had a similar heart problem (I can't remember the specifics) and had heart surgery as an infant. She is now 4 years old. Around the age of 16, she will need to have another one.
I do hope that you will write a letter to the original pediatrican and tell her that ANYTIME an infant is retracting, that she needs to pay attention to it and not just pass it off. Include your child's diagnosis. The reason to do this is to help other children.
This will all be a process, and the best thing you can do is follow the process diligently. Though as a nurse you know so much more than the normal layperson and can be overwhelmed by that knowledge, try to use it as "knowledge is power" rather than being frightened. That is the best way to help your son.
Prayers and well wishes for you and your son~~