Hi and welcome to HCM.
It sounds like varicose vein
or epididimal cyst
and usualy isnt anything serious. Especially considering that it last for 3 years. If I am right then treatment isnt needed.Just watch for any new signs such as pain,swellings or urinating difficulties. It can aslo be ingunal hernia
if this is prominent when you cough
or do exercise. You can do ultrasounds to verify the exact diagnosis but I dont think you should worry.WIsh you good health.