Welcome to the STD forum. It looks like you hit return an extra time. Your question appeared twice; I deleted the second. You should use the contact link to communicate with MedHelp administration and ask if they will reimburse your credit card for one of the charges.
Syphilis currently is one of the rarest STDs in the US, and most cases are in gay men. Your partner clearly has a very low risk profile for syphilis and other STD. Also, transmission of syphilis by oral sex is quite unlikely, although not zero risk. Finally, are you sure you weren't tested for syphilis in December? Syphilis blood tests usually are automatic when someone is tested for HIV, gonorrhea, and chlamydia. You should call the clinic and make sure; if you had a negative blood test for syphilis, then for sure you didn't catch it.
The sores in your mouth don't make much difference. Canker sores are painful, syphilis chancres are painless. Anyway, it is too late for a chancre; that would have shown up within 6 weeks of the exposure, not several months later.
Bottom line: Almost certainly you don't have syphilis. Call the clinic and see if a test was done and negative in December. If not, you can have a syphilis blood test now. You can expect a negative result.
Best wishes-- HHH, MD
That ends this thread. I won't have any further replies.