i would have to see his scrotum and examine him to really make a comment so i would suggest that you bring this up to his pediatrician. at age five the testicles are small and tend to be "migratory" (can travel up higher in the scrotum rather than hang low like in a man).
is it normal for my 5yr old scrotum to look as if it's shrinking not relaxed like a bag. the scrotum seem lax and dull almost without life. never complained about it except for pain on his penis sometimes. just wanted to know if it's something or nothing. thanks