I experienced the exact same thing last month and after a week it went away, however this week it's come again except with a rash which seems to fit the discription of syphilis. I don't know really, i'm not a doctor, but i'm going to get checked and so should you.
I never thought it could be infected by a razor, that seems very plausible. With all the bacteria and tiny rust particals on those things we should be more careful ;)