In reply to KingStapo:
See your GP. You might not want the advice, but it's what you actually need. TBH, it does sound like a variocoele, but out of interest have you been vasectomised?
I found a bit of a fluidy lump a few years back; wasn't worried, as it was non-painful, but was marched up the doctors PDQ by the good lady, and sent for a scan. Whilst there, I found out that it's a common sequel to vasectomy.
On the other hand, a guy at my vet school apparently sat through a whole term's worth of cancer lectures, whilst one of his testicles was slowly growing and getting more and more painful. By the time he sought help, he couldn't ride a bike and it had already started to spread. I think he was OK in the end, but it was very touch and go.
Always worth a visit to the quack.....
Martin