Hi S.,
When it comes to my kids, I don't take any chances. You are asking for advise because you know something is not right....call your pediatrician and get your son checked....you never know...I don't want to scare you, because I don't know you, but I know of horror stories that started out with a little girl having bad breath...it was just the beginning of something no parent ever wants to even think about happening to their children.
In my opinion, better safe than sorry. It will give you peace of mind.
Take care of you and yours,
P.