This exposure was about 4 to 5 weeks ago . i took a ora quick yesterday which came out negative.
Oral sex has zero risk. To answer your questions, ars rash from what I have read are flat & non itchy patches. If testing will make you feel better, a 4th gen ab/ag test can detect infections after 28 days, although you will need a confirmatory test in 3 months. but you don't even need it in my opinion. You should consult a doctor if the rash persists though, it could be something else, but HIV is not your concern.