What Causes Painful And Swollen Testicles?

hi. My testicles have been hurting and swelling for about a year for about 15 minutes each time but it was only like once a month til last month. Its been happening almost every day and last week the pain got severe when i attempted to masturbate to release my sperm. I thought it was back up sperm because lately when I ejaculate very little sperm comes out. Last three nights I played basketball and each time my testicles started hurting. Somtimes it seems only the right one is in pain and swells but mostly both. On the symptom diagnose it said automic neupathy, low sperm count, and testicle cancer. What do you think?