Testicular pain - #10216

Hello, when I go to the gym or do physically demanding activities, sometimes (not always) I start to feel pain in my left testicle, and when urinating I feel mild pain in the lower abdomen. The pain appears only after exercising or after other strenuous physical activity. The pain goes away over time. When I do nothing strenuous, I feel no pain, but after a longer break, when I return to the gym, the pain comes back. The testicle does not look different than normal, it is not warm and not swollen. When urinating, the head of the penis does not hurt, but my lower abdomen does. When I lie down, I have to stay in a position where I do not put pressure on my testicles, otherwise it hurts. I am 16 years old and I do not know what to do