Can I ask where the testicle pain is? Like right one, top or bottom? I have had this a few times to the point where it hurt so much I couldn't walk properly and my back hurt so much it was hard to get comfy. It was something called Epididymitis which healed after having antibiotics.

According to my GP once you've had it once it can come back.
http://en.wikipedia.org/wiki/Epididymitis