Oral Syphilis?

[APHK]

I gave unprotected oral sex to another man 4 weeks ago and took semen in my mouth. I had very mild inflammation of the glands in my throat, but that seems to be passing and other friends have similar complaints of bugs causing a sore throat. . I've noticed a very small lump on my hard palate for the last day or so. It is just a small lump that is tender (maybe due to the fact that I keep pressing it), doesn't look ulcerated and is a similar colour to the rest of the palate (red/white).

1. Does a syphilis chancre begin like this and stay non-ulcerated for that length of time?
2. Is the palate a likely place for a chancre to appear hrough giving oral?

Thanks

[Life360_Dave]

Hi, first of all its a matter of contracting it so if he did not have an open active canker sore on his penis (which i doubt he did as the oral would have been painful) and you did not have an open sore in your mouth for the germs to enter, you were not exposed to syphilis in the first place.
1. syphilis are ulcerlated not a lump
2. no its not

[APHK]

Thanks for replying so quickly. I took a 1g of Zithromax approx 3 weeks after exposure (with no symptoms other than paranoia). Would that prevent a chancre from forming?