Pain in my left testicle for a few days now?

For a few days now I have been feeling a mild occasional pain in my left testicle, there is no lump, swelling or change in appearance as for as I know, and the pain is mild (comparable to the after-pain of accidentally lightly knocking testicles), and comes in short 1-20 second bursts 'infrequently', but I am still worried. It doesn't hurt when I touch it, the pain just comes in short random bursts. It also doesn't bother me a lot as the pain is so mild (more or less just an uncomfortable dull achy pain), but I am still worried about what may be causing these infrequent bursts.

A day before I started to feel the pain, some of my clothes were currently being washed so I had to wear a pair of very tight trousers with no underwear for the day (out of desperation) and a couple of times, I flinched and jumped up with pain as sometimes when I'd move, the trousers would suddenly tighten and restrict that area. Having said that, this was just for one day out of desperation. Is it possible I could've caused some damage by wearing the tight trousers (if so how long might it last?) or could it be unrelated entirely?

Help appreciated, thanks

I doubt you will have knocked anything by wearing tight trousers... I'd get to the doctors... Not through any immediate panic but given the nature of the area... You could have a varicocele which is a essentially varicose veins but in your scrotum... It's nothing to worry about but get checked out to rule it or anything else out...

Or Epididymitis. From many reports it is difficult to diagnose but it was no problem to my GP when I gave him my symptoms that remained after having had prostatitis.

Please, please see your GP... I very much doubt he/she will find anything wrong with you but you must start your investigation at the Gps before getting worried or thinking about any other investigations.  Makes sense?  So do it!