I am 19, my left testicle has been like this since I was like 12 or maybe younger. My parents where told to take me to a specialist but they could not afford it so now I am going to make a appointment. Its only me left side. The area to the left of my penis and above my testicle (like where your thigh and waist line) the left side is hard/stiff and if i push down on the opposite side it feels like I can push down with ease. At random times my left testicle will shrink and look just like my right testicle. I think when my testicle swells up it is solid like and will hurt if i squish the wrong part. I might be all over the place in my posting but I tried to describe this the best I could.
Its normal.
While there may be a problem you might want to have checked out everybody has different size testicles.
If it has been like this since you were young it would suggest that it is completely fine and theres no need to worry. However, it strikes me odd that you should feel pain in your testicle which obviously you shouldnt. Then again it depends how hard your 'squishing' it. As im sure your aware if a mans genital area is hit even a slight tap, if it is hit wrong it hurts like crazy. I think a routine appointment with your GP is probably a more sensible thing to do first. Explain its been like this for a while, but the pain causes alot of discomfort. Then you might be led in a better direction and find its nothing to worry about