If the scrotum is very sore you can go to the ER. The most dangerous and very urgent condition, referring to testicles, is testicular torsion. If you had such a condition the pain would be so unbearable that you wouldn’t have time to post. Other reasons for scrotal/testicular pain can be an infection, an injury, bleeding, etc.
You may want to consult your primary health provider and a urologist, if necessary.