Go to a real good doctor for a check up of Testicular cancer. I do not mean to scare you but this is what you need to do. It is could be testicular cancer which is cured easily if caught in time. My friend's brother had a huge tumor on his testicle, the size of an orange. And it spread to his intestines. Lucky him he was saved by surgery, and chemo. Please get a check up with a very good doctor.