Hello. I have a question of a delicate nature... literally. One of my testicles is very sore and has been for approx one week. I run a lot and thought that might be the culprit. I have not run in 4 days but problem is getting worse. Cannot think of any kind of injury I could have sustained.

Unfortunately for you, this is something you really need to take up with a doctor. We can't diagnose this. It could be anything from being rubbed wrong from running up to cancer even... there is just no way for us to know so to be safe, you need it checked out.