Ok, thanks... I almost forgot the issue, but then, I remember that syphilis canker can be in mouth, and bang, worry again. Now is a problem of possibilitys, the risk is low, but there is risk for a STD, and being in a relationship as I am that´s a bit of concern. Thanks anyway.
In theory, syphilis can be transmitted by kissing, but it almost never happens. Don't worry about it and don't get tested.
Your questions about other STDs were answered in your other questions. No need to repeat.