Hi,

From the sound of it this sore comes and goes. Does it coincide with an outbreak of herpes or is it independent of this? If it doesn't appear related to outbreaks it may simply be a patch of dermatitis, or sweat rash perhaps.

However, you seem to be wondering whether you have a chancre? A chancre is the first sign of syphilis. It usually appears on the penis or scrotum, is round, and in appearance looks like layers of skin are missing. It too may come and go.

So, whilst your skin condition may be nothing in particular, it could be something significant. Clearly the best thing for you to do is be checked out and avoid sexual contact until you are. The skin complaint doesn't need to be present to have a blood test for syphilis.