Yes, it could still be syphilis. You really need to see a doctor. Not doing anything about it won't make it go away. If it is syphilis, even though the sore goes away, the infection doesn't. It just keeps progressing, and in time, can do some real harm to you.
Aj
The bump has been going down, could it still be syphilis or something else
I'd get this checked. It sounds like it might be syphilis.
Aj