Hi Peter.
How are you doing?
There are many considerations for a lump in the testis. It could be a part of your epididymis that is easily palpable. It could also be a hydrocele/hematocele of the testis or spermatic cord, a scrotal inguinal hernia, or a spermatocele. Testicular cancer usually presents with painless testicular mass.
I would suggest you have yourself physically examined by your doctor. Further tests need to be performed like a scrotal ultrasound and blood tests.
Good luck.