Thank you for your query.
You mentioned that your son had a heart murmur
at birth. What was the cause of it and what was the follow-up report on it? This will help in guiding you further in this case. However, the family history and the pain should not be taken lightly. It would be appropriate to consult your doctor and get a complete work up done.
I hope I have answered your query to your satisfaction.
Wishing your son all the best.