What a relief! We saw the pediatric cardiologist and after various tests, he has ruled out our biggest fears. She does not have a hole in her heart. She has a "flow murmur" which on a scale of 1-6 (with 6 being the worst) is a 2. The reason it seemed so severe at the urgent care was because high fevers cause the heart murmur to be more prominent. So we were given a whole bunch of information (signs it's gotten worse, etc.) and we have to make sure that if she's ever sick and goes somewhere outside of her pediatrician's office, we have to inform them that she has a flow murmur so that they don't run unnecessary tests and focus on the heart v. what she's actually sick from.
What a relief! I mean, she still has a heart murmur and that's not exactly "nothing", but we're told that a 2 is nothing to lose sleep over. She's healthy, she is off the charts for height, she has energy, etc.
I swear, when the urgent care pediatricians suggested that we have to get her checked out because what they were hearing in her heart usually meant there was a hole there, I was mortified. But now it's all ok.
Life is good - now, if only we could get that house sold...