What could cause persistent sore throat after oral sex?

After engaging in oral sex with another man, I developed a sever sore throat the following night which, though severe for only a brief period has persisted for 6 weeks, with redness on the sides of the throat flanking the uvula. I was treated with rocephin and zpak 10 days post event with no improvement, then again with doxycilin 3 weeks post event with no improvement. At about the 5th week, I noticed a tiny sore, dark red spot inside my cheek surrounded by pale redness in a circle. Same thing in another location a couple of days later. These lesions faded away within a day. Then this morning I experienced soreness in the hard palate which was about a centimeter in diameter of light redness. I thought there was what appeared to be thrush on the back of my tongue for a brief time, which followed the course of doxycilin. Small itchy bumps appeared on the abdomen in the last days of doxycilin also. Two throat swabs have been negative for gonorrhea at 7 days and 3 weeks. Negative for HIV using the HIV 1/2 antigen antibody, 4th generation w/rfl, which the counselor said was definitively negative at 30 days post event with no need for further testing. So, what could be happening? Thank you!!!