Thanks for your query.Based on incomplete information provided in your query it is difficult to conclude.Is swelling
superficial just beneath the skin or deep near the Testicle ?Do you have any fever
It may be either Epididymitis
or a Sebaceous cyst .However final diagnosis can be confirmed only on clinical examination So please consult qualified Urologist
or Surgeon for clinical examination to confirm the diagnosis.
You may need to take antibiotics like Doxycyclin along with anti inflammatory
drug like Diclofenac
for a week.