I wanted to know, will a syphilis test give a false negative if you already have the bump on your genitals. I had an unprotected blow job from a woman of unknown status in november. In January a bump appeared on my penis. I have a 3 month conclusive HIV test. I had an std test for syphilis at week 7 after possible infection. Will I need to retest for this, or can I assume I am in the clear since the I had the bump when I had the test. I had an itchy rash for about 2-3 months until a dermatologist diagnosed me with exyma. Should I assume Syphilis is out of my concern since I had the negative test or should I get tested again.