When I hit the 2 to 3 week interval of not having ***, & I'm in the gym a lot, and around ladies that make me hard, my balls get so tender, & sore. Then they later leak *** even if it goes soft. It feels like I have to ****, and then the white protein just globs out. Funny it actually feels not bad, and smells good. Weird ****. It is blue balls, and it stops when I start cumming regularly. I'm a control freak, and I masochistically do it to torture my self, and reap the energy benefits of the phenomena. I think from too many boners, and zero squirts, causes the body to produce an excess in semen. Your system may be thinking your going to get busy, and then your nuts just swell. LOL..And if that doesn't cure it, then a few good Nocturnal emissions does. hehehe.
A lot of men experience some slight pain in the testicles when they are aroused and have not had an orgasm in a while. But it sounds like your pain is more intense. Does the pain only happen when you are aroused or close to your girlfriend? Does the pain go away after you masturbate? Do you notice any swelling or lumps on your testicle? If the pain continues or gets worse, you should see a doctor to make sure you do not have an infection.