Hi, I think that you are just fine. Herpes simplex virus is not really a serious condition and anyone is supseptable to it because it is a cold sore, fever blister, and some call it night fever. One of the reasons that I think you may have had some of the symptoms is that the person's mouth was not sanitary because that can cause yeast infections, so I guess it could cause you to experience itching, burning, and etc.
The only possibility of an std from that exposure would be herpes 1 on the genitals, which is HIGHLY unlikely, especially if you never saw a sore. Anyway, persistant symptoms like that sound like they could be psychological more than anything. It's not an std, but you could see a urologist if it really is that irritating.
The exposure you describe was virtually zero risk. I'll go straight to your questions.
1) No undetected STD is likely to last this long, and your symptoms don't sound like those of any STD. 2) No, the symptoms do not suggest herpes. 3) Since you have no STD, there is nothing to warn a partner about. 4) Having seen 4 different providers without a clear answer, I see no value in seeing yet another one. 5) Your symptoms don't suggest a prostate gland problem.
You can be completely certain you don't have an infection, or anything else that will ever harm you or a partner. Most likely you will just have to live with the symptoms. Just as some people have unexplained aches and pains of various body parts (back pain, unexplained abdominal pain, headaches, tingling of an extremity), others have such problems of the genitals. In other words, not every symptom means disease. I suggest you put it out of your mind and move on, secure in the knowledge that no harm will come. Simply knowing there is no danger often is helpful--reflecting the common involvement of emotion in how we perceive pain and discomfort.
Good luck--- HHH, MD