Is it around the back of your testicle? It could be where the Vas Deferens connect to your testicles. If you have similar lumps on your other testicle, chances are it's normaly. Normally lumps are hard and stationery, especially on the testicle.

if you are experiencing any pain or discomfort, you should probably get it checked out. Testicular lumps aren't meant to be left untreated!