Occasional testicular pain

Very, very occasionally, whenever I perform random bodily functions (sneezing, coughing very hard, having a bowel movement), I get this very intense discomfort near my left testicle. It's not a sharp pain, but it's like this high pressure feeling in one of the tubes. This has been happening to me on and off for a few years now, but I must stress that it's -very- occasional. Like, I can only recall maybe a few times when it's ever happened.

The reason I have come here is because I decided to perform a cursory examination on the area. No lumps to speak of, but I discovered that the tubes leading my my left testicle are a lot more firm and pronounced than the ones leading to my right testicle (near where the discomfort occurs).

I'm going to tell my family about it and eventually my doctor, but I just wanted to get an idea as to what could be the problem (if anyone knew) before I go.