Welcome to health care magic.
1.Pain and swelling of the testicles are seen in case of infection / inflammation of the testis ( short history suggest)
2.Running and jumping do cause such effect when the gravity falls on the testicles and hurts.
3.Ideal thing in the case will be an
ultrasound scan - that will help in evaluate the cause, presence of torsion, vascularity , free fluid, chord,
epididymis status.
4.In this condition loose clothing's are not recommended -rather some thing to suspend them.
5.The treatment in case of inflammation / infection is a course of antibiotic will help, other pathology - treatment accordingly. Good luck.
Hope i have answered your query.
Any thing to ask do not hesitate. Thank you.