I definitely agree that prostatitis could be the cause of your problems. It does require a long course of antibiotic therapy, normally.
The antibody test for HSV 1 is not great and misses 1-2 out of 10 infections. The western blot would be better at picking up HSV 1 infection, if you want to know about that.
I would recommend the western blot if you have trouble believing the negative screening test.