Hello,
It can be a spermatocele. Spermatocele is a retention cyst of a tubule of the testis. Small cysts are left as such but if it is causing pain and discomfort as in your case, then surgical intervention needs to be done. It is done under local anesthesia on an OPD basis and there is no removal of testis.
Sclerotherapy can also be done but it is usually not preferred.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.