It could be puberty.
It can be due to trauma or infection.
yes dont do it you'll get a mouth sore too
This is normal for a boy in his early teens and it won't last long. Swelling around a boy's nipples is one of the several changes that come with puberty.See the Related Questions below for "What is puberty?"----
if your guineapig has nipples means it still is a boy.
Boy guinea pigs don't have nipples.
darker nipples
no it is not
Sure he can be.
Nothing comes out f them.
its because when you are a zygote then you can either be a boy or a girl so the nipples develop anyway
The best way to deal with an out of control teen boy is to send to military school
is a boy