Yesterday morning I noticed a tiny looking blister, size of a pin head, on the shaft of my penis. I have no pain or discomfort, and I have been with the same partner for 9 years. My legs are a little sore, but I work in a enviroment that I walk several miles a day, so this is a normal feeling. (Seen that muscle pain can be a symptom). Anyways, I have only had sex with two people my whole life, one being my wife, and the other being almost 10years ago. Is it possible that this could be a sign of a STD? I have looked at tons of pictures online, but they all show clusters of blisters, not just one tiny one. Anyways, it scares me since I have never noticed anything like this before. What else could it be? The blister is about a inch up the shaft, and no other blisters anywhere else. Thanks again!