Personally, i don't think you have neither syphilis nor genital herpes.
If this was indeed a case of syphilis, your bump should be transformed in an ulcer till now.
Genital herpes is usually presented with multiple small red bumps which later develop into painful blisters, following crusting, forming a scab and healing.
What's the color of this bump?
Is it soft, raised mass with a smooth surface?
Does it feel itchy?