What Causes Shivering In Penis?

For the past two-days I have developed a sensation of shivering or shuddering, for the lack of a better description, in my penis. It started out intermittently but now is constant. I am urinating normally, no constant urges, no discharge and everything looks normal in fact there is no visible signs of the sensations. It is stricktly an internal feeling though the penis and not so much in the body. I had a prostate exam and urinalisys as a part of my yearly medical exam and received an all clear on those tests.

It is not painful but it is rather annoying and discomforting while I have been at work. I have never heard of this type of condition and when I attempted to research the internet on the topic, well you can imagine the links that displayed. I am very serious about this and prior to contacting my doctor I wanted to see if there is any known medical condition for this sensation. Thanks, I appreciate your assistance.