It could be Hydrocele
or Testicular Tumour.
Thanks for your query,based on the facts that you have posted it appears that you have swollen testicle to the extent of 5 times bigger than normal.
This is most likely to be due to either Hydrocele or Testicular Tumour.
Please consult qualified Urologist
for clinical examination and get following basic tests to confirm the diagnosis.
1) Routine Urine tests and blood tests.
scanning of the scrotum
Further investigations and treatment will depend upon the preliminary diagnosis.
Hope I have answered your query ,please feel free to ask if you have more questions ,
I shall be happy to help you
Thanks and Regards.