Thank you for the query.
First of all some good news for you. If it were a testicle cancer, you would not be able to survive with it for 4 years. Moreover, testicle cancer is rare condition. Most likely you do suffer from inguinal hernia
which has moved to the scrotum
. Especially if you do associate it with heavy lifting. The pain can be caused by this hernia however it can be due to urinary tract infection
I suggest you to visit general surgeon
and have physical examination. If any doubts about this lump, testicles ultrasound
should be performed. Urine analysis should be done as well.
Hope this will help.