Welcome to the forum. I'll try to help.
You are overreacting to a low risk event. As you learned from reviewing other discussions on this forum (thank you for doing that research!), and as you were informed on the herpes community forum, neither herpes nor any other infection can cause symptoms within a few hours of exposure. And there are no STDs that cause the sort of symptoms you describe, which are typical for genitally focused anxiety. Finally, oral sex is a low risk exposure for any and all STDs. To your specific questions:
A) In theory, you could acquire any of several infections, including herpes due to HSV-1, gonorrhea, nongonococcal urethritis (NGU), or syphilis. In reality, all of these are extremely rare after a single oral sex exposure -- and your symptoms don't fit any of them.
B) If your partner has oral herpes, and if that person's infection were active at the time of exposure, the chance you were infected might be something like one in 1,000.
C) You really need not be "on the lookout" for anything. This is not the sort of sexual exposure that most people worry about at all, and neither should you. However, for 100% reassurance, I support your plan to find a local health department STD clinic. Follow their advice about testing.
In the meantime, stay mellow. This really isn't an exposure you should be concerned about. Don't confuse your apparent anxieties about a sexual choice you regret with STD risk. They aren't the same. Deal with the former as you need to, but stay relaxed about the latter.
Regards-- HHH, MD
Thank you, Dr. Handsfield. I really appreciate your more-grounded approach regarding the efficiency of STD transmission than perhaps some of the more dogmatic public health advisories I have read online. I remember a couple years ago researching information on HIV transmission for a health care policy project I was working on in class. I saw your responses to some of the people who similarly were worried about HIV transmission through oral-genital contact (how I found out about this web resource). I thought at the time that they were freaking out for no reason, in the face of a mere "theoretical risk". Now I guess I can empathize with them in a different respect.
My follow up question is an attempt to bridge this right brain/left brain conflict and help get over my general anxiety. I have been feeling some itchiness in my public region throughout the day. Earlier tonight I even saw a pimple in my public hair which I tried to pop, but caused pain in the underlying muscle. I've since been unable to find the pimple. I know logically that I could be attributing my itchiness to an IO, but situational factors (it's hot out, no AC) could also explain it, I guess. Given that many cases of herpes are asymptomatic, how do I know that the itchiness I am experiencing is a result of anxiety, and not a precursor to an initial outbreak?
I find myself either legitimately concerned about my health, or turning into one of those terrified posters who is ignoring realistic probabilities of having an STD.
obviously that should be pubic*, computer autocorrected.
Initial herpes doesn't cause itching as the first or main symptom, and a pimple in the pubic area is almost never due to herpes. "Situational factors" plus your anxieties about the exposure are almost certainly the explanation.
For an HSV infetion to take, the virus usually must be massaged into the exposed tissues. Accordingly, initial herpes almost always is at the site(s) of maximum friction during the exposure that resulted in transmission -- in this case, the penis, not your pubic area.