Extreme pain in my lower right testicle?

Yesterday, after ejaculation, I used the washroom. Shortly after urinating, I got an extreme pain in my lower right testicle right below the ball. It is not swollen. This has happened to me once before though. Same situation, after ejaculation. But the pain was mild, and went away shortly after. So I guessed it was just random and nothing to worry about. But this time, I could not bear the pain, so I had to let out a moan in pain for it lasted much longer than before(if it counts I say the pain is around 7-8 out of scale to 10). I'm confused and do not know if i should visit the doctor soon as an emergency or not. I wanted to know if its something i should visit the emergency room about? I am 14 years old. I also worry if its an STD. I highly doubt it. But sometimes you just never know. Someone please help?