is a fluid filled swelling in the epididymis
,structure present above testis.Antibiotics have no role in that disease.
If the swelling is responding to antibiotics,it can be epididymitis
But,the swelling which you are palpable can be epididymal cyst.
It has to be removed by surgery
Please get an ultrasound
scrotum for correct diagnosis.
Consult your doctor and proceed
Wish you good health