A couple of years ago, I had a couple with whom I only received oral sex (that was the only sexual encounter that there was), a couple of weeks ago I was worried about having contracted HIV, since I have a small infection in my throat, and I have had two canker sores in the last month, but I do not know if this was caused by my own stress, and 5 months ago I did some blood studies for school purposes and all the values were normal. What should I do? Is my concern justified?