Thanks for your query.Based on the facts that you have posted it appears that you have what is called as Spermatocele
This is a cystic swelling that contains sperms and attached to epididymis
of the testicle.
This can be confirmed only on clinical examination and Ultrasound
scanning of the scrotum.
Please consult qualified Urologist
for clinical assessment .
Normally it does not require any treatment unless it is painful.