It is rare but possible to transmit syphilis by open mouth kissing.
No further discussion of it; this isn't your thread.
I thought it was not possible to catch an STD through kissing?
Welcome to the STD forum.
I would have thought you had been tested for syphilis following your question and replies on the HIV international forum 2 months ago. But apparently not (?). Your symptoms don't really suggest syphilis. It is very unusual for syphilis to cause lymph node enlargements as the only symptom. (Most non-health professionals cannot reliably evaluate their own lymph nodes. I do not accept that yours are significantly enlarged unless that has been determined by professional evaluation. And in that case, medical evaluation should be underway to determine the cause.) In any case, have a syphilis blood test now. You can expect negative results -- if indeed negative, it will be 100% reliable.
In the event you have syphilis, your more recent partner definitely would have to be informed. Syphilis certainly can be transmitted by oral sex; infrequently by kissing but possible. But cross that bridge if and when you come to it. There is no point on dwelling on it now, since I expect your test to be negative.
Feel free to return to tell me the test result, but not until then. There is nothing more I will be able to say otherwise.
Regards-- HHH, MD