Welcome to the forum. Thanks for your confidence in our service.
Syphilis can be transmitted by oral sex, but it's uncommon. Body contact ("grinding") without penetration also could do so, theoretically, but very rarely. In addition, assuming your partner's background is as you describe, it sounds unlikely he as been exposed or infected himself. And based on your description, doubt your oral lesion is syphilis -- and if it heals and returns to normal within a few days, you'll know for certain. Once a primary syphilis lesion (the chancre) starts, it lasts 2-6 weeks.
As for HIV, it's virtually never transmitted by oral sex. For sure no worries there -- and as for HIV, it seems your partner is not likely to have HIV. But since you're worried, why not call and ask him? Maybe you'll find he's as worried about your STD/HIV status as he is about yours? Maybe you'll decide to go get tested together; if both negative for HIV, you're both home free.
Or if you remain nervous, have syphilis and HIV blood tests yourself ~6 weeks after the event. If you do so, I'm confident the results will be negative.
Best wishes-- HHH, MD
Thanks for the thanks. I'm glad to have helped.
Thank you so much for you timely response. It is perhaps possible I am driving myself nuts because of the huge guilt I am carrying. I did ask him before and after our encounter to which he replied, he was std free. I hope he was telling the truth but I wanted some kind of clarification, which you have provided, regarding my risks since I have to wait a long time before I can be tested. I am ignorant concerning the facts of hiv and syphilis I appreciate your response Dr.