My oldest son had enlarged nipples at that age. You know how you see very fat men who have breasts? He didn't look like that. It was just his nipples that were enlarged. All the rest of him was thin.
For him, this lasted about 4 years and now his nipples are flat. During the interim he would wear underarmour swim shirts or some other t-shirt to swim, because his nipples were really obvious. They were like the size of Hersey Kisses.
He is a Rugby player and very fit and trim and masculine. But when he was an infant he had the most severe acne I've ever seen on an infant. I wonder if maybe he has hormone swings that caused both the infant acne and the nipple swelling.
Best wishes. This too shall pass. ;D Just buy underarmour or other tshirts and wait it out.
I don`t think it was normal when I grew up but nowadays our environment is bombarded with estrogen in the food chain and estrogen-like chemicals. I do see that adolescents of both sexes look very "feminized" but it usually seems to straighten itself out. If you are worried, I would get his hormonal balance checked.
The whole situation of hormonal disruptions is pretty disturbing but that`s a whole separate debate. Estrogen-injected cattle, birth control pill residue in our rivers and lakes, rare side effects of steroid treatments, pseudo-estrogen from soy products, pseudo-estrogen from BPA in baby bottles and cans - nothing will ever be proven but there sure is a hormonal mess out there...