Rolling Over at Night

My son is gonna be 5 months old on the 20th this month. Recently he’s started sleeping on his side at night which didn’t bother me that much he looked safe in his position but shortly after that he started to roll over on his stomach with his butt up in the air a little and head slightly turned. This position makes me so nervous because I’m concerned about SIDS!

Is this something I really need to lose sleep over? I am nervous to sleep because I know he may roll over on his tummy. Is there ways to prevent him from doing it?