oczack

For the past 3 yrs I've had a burning in the urethra after ejaculating. It doesn't last long maybe 10 to 20 sec. or so. and it's no real intense but I've come to expect it and it bothers me. I don't have it always but most of the times.It seems that if I orgasm more frequently, maybe 3 or 4 times a week or occassionally more, the burning is much less. I feel a very slight burning up in the urethra in the area of the bladder after urinating but not very intense. I've had all the STD tests for HIV, Syph.both Heps.,Herpes I & II, I tested pos. for the oral herpes but not the genital type. I had those tests twice and I had the gonnorhea and the chlamydia tests 3x's,, all were negative excepting the oral herpes. I am 61 yrs old and my wife doesn't experience any difficulties or discomforts or obvious symptoms. I went to the Urologist twice and her perscribed doxy. and then a lengthly low doseage of trimethoprim. None seem to help. I've had digital rect. exams the llast being 2 yrs ago and PSA tests. Of course the burning was during the times of the exams and tests but nothing changed. Dr diagnosed me a acute prost. non bacterial as nothing showed up inthe urine stick tests. He had said that a urethral exam with a scope or tube would be done if things got worse or came back. They are less than the original onset but still there. I also occassionally experience some discomfort in the lower urethra between the rectum and the testicles when sitting too much but it's not as bad as after ejaculation. I sit for pretty long spells. I also feel the slighter burning sometimes after a bowel movement. The burning I experience is most often in the area between the rect. and testicles but occassionally further down toward the tip but not often. Like I said if I only have sex once or twice a week the burning is more intense than when having sex more often but ot's still there.
Is it possible if oral herpes was in the urethra I understand that can happen and there are no visable signs on the penis no sores or bumps,if the herpes was up inside could it have lasted for 3 yrs without going away for a while and then returning as I understand genital and oral herpes does go away. Is it possible that HPV even without any visiable warts could cause something like this ? My urologist gave a couple look arounds on my penis when he examined me and if there are any new bumps or wrinkles I'm not aware of it. I know I've gone on quite long but i hope you could give a little advise and some ideas as to what might be going on here. Thank you.
Concerned old dude.