Hello,
There are many possibilities for this lump.It can be a hydrocele or varicocele.Hydrocele is a collection of
sterile fluid in the cord attached to the testicle, which is invariably harmless. Left untreated, a hydrocele
can grow to a large size and cause discomfort, so they are usually best drained early.
Varicoceles are similar, except they are caused by enlarged blood vessels. Both may require surgical removal
in severe cases. Hydroceles can be easily demonstrated by shining a flashlight (transillumination) through the
enlarged portion of the scrotum. If the scrotum is full of clear fluid, as in a hydrocele, the scrotum will
light up.An ultrasound may be done to confirm the diagnosis.It is the most accurate diagnostic test for this
condition.
Other possibility is of infection (Epididymitis or Orchitis). If the infection is caused by bacteria, your
doctor will prescribe an antibiotic.Blood tests can confirm it.
I feel that you should take a second opinion from a urologist and get yourself evaluated.
Take care and regards.