Singular tiny spot on scrotum, kind of looks like a pimple?

I am 14 years old and I am only about 6 months into puberty. I have never had any sex in my life. The other day in school, I noticed that a part of my scrotum hurt a little bit. When I got home, I found a very small white spot on my scrotum that stuck out like a pimple. It was probably only a mm in diameter, and it hurt when I touched it. Today when I got home, I checked it again. Now it is way shorter and doesn't hurt as much, and it is red. Is this a pimple? Do you think the pimple head just fell off during the day? Hope somebody can help!