In Chinese medicine this is some times related to your body's status becoming too COOL or lack WARM. E.g. older persons who drinks too much tea will cause this balls pains. What happens is the veins of testicles got swollen, even a slight swell is very painful, and doctors can not visually see any swelling. But after long time it can become very large and obvious.
That is very painful and Tua Lan Par.
Your must adjust your diet towards WARM & stop taking the COOL stuff if that was your case.
In Ang Moh medical terms it is varices formed in testicles veins. Or Varicose Testicle.
http://www.malereproduction.com/14_varicocele.html
The western doctors will do surgical repair on your balls if it gets BIG enough. But by then your pains will be Si Beh Jia Lat. The simple thing is to consult experienced Chinese physicians and take herbs plus learn from them how to modify your own diet.
Usually they will tell you to avoid a list of things including tea, and then give you WARM herbs.
Wish your balls luck!