are canker sores related to ars or hiv? before a couple of weeks i had uprotected deepthroat oral sex with a prostitute..at 21 days i had an hiv test in a GUM clinic (i dont know what tests they used, UK) came back negative as well as test for other stds i had only urethritis.. the forum helped me a lot at that time and thank you... now iam in the sixth week after the incidence and i developed a very painful canker sore....i dont know if i need to be retested now please help me ...