Hi baby rn,
Welcome to the forum, and thanks for sharing your son's experience's. I don't know how new you are to the idea of reincarnation, but it's nothing to worry about and it's perfectly normal for a child to talk about their past life, it's not something that will necessarily haunt him forever, most children remember between the ages of around 3 and 7 before they become more involved in their present life and then they begin to forget.
It's my opinion that all children remember their past lives, but most parents dismiss it as imagination. You are doing the right thing by letting your son talk openly about his memories, just go along with what he is saying as if you already know about it, try to join in with his conversation, maybe get him to draw some pictures of what he remembers, and like Vicky said, make sure you write everything down and keep it safe.
I would highly recommend investing in Carol's book
Children's Past Lives, as there is a lot of information there to help parents like yourself to deal with a situation like this, you can read the first chapter
here.
I hope you enjoy the forum and keep us updated with your son.
Chris...