I have had burning in my penis, pretty constant, for 5 days. I had unprotected oral sex with a new partner 12 days before the symptoms appeared. The inside of my urethra looks red. I was tested for Chlamydia and GC, as well as Syphillis with Negative results. I was given a single does of Azithromycin. The symptoms have not subsided. Can someone give me some ideas as to what is going on?