thanks for using health care magic.
Your son has a very contributive history that warrants continuous
attention when ever need arises. People with past history of
heart surgery or heart malformation are predispose to infections
of the heart called infectious endocarditis
which could explain the
symptoms your son is having.
It is advisable to take him to the doctor for an evaluation and some workups
such as cardiac ultrasound
, complete blood count
, blood culture
as the case may require.