Okay, so anxiety is a thing for you, no? Do you see anyone for that? Are you on treatment for that?
Syphilis is very uncommon in developed countries, like the US, Canada, UK, etc. You used a condom and oral sex is lower risk than vaginal or anal sex, so I wouldn't even worry about syphilis.
Also, it doesn't look like a dry spot. If that doesn't clear up, see a dermatologist - maybe eczema or allergy or something.
As far as herpes, have you ever tested? You had this spot for over a month? Almost 6 weeks? That's not herpes. A herpes sore wouldn't last that long, which I'm sure your Googling would have told you.
I don't think you should test for herpes. The hsv2 IgG has false positives, and I don't think your anxiety can handle it, and you had very low risk for it.
I can tell from your previous posts that STDs are a source of anxiety for you, and though I don't understand why, you can reduce this. Before having sex with any new partner, test. Ask your partners to test. Get counseling.
You are doing yourself a disservice by only focusing on STDs as a cause of symptoms. Sometimes, dry skin is just dry skin.
Your questions have been as fully answered as possible in this, or any online forum. As noted, please see your doctor if you have further questions.
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