Simple question: Will a syphilis test definitely come back positive if a chancre is present? I had unprotected oral sex performed upon me about 3-4 weeks ago and noticed a suspicious red bump on the tip of my penis a couple of days ago. I had a syphilis test performed yesterday but the doc wasn't very knowledgeable about syphilis and wasn't sure if the test would be conclusive.
Please advise, and thanks in advance!