most CSW have no HIV or other STDs. Even if the CSW is HIV positive, the chances of you getting it via an unprotected encounter is still extremely low (less than 0.1%).
the rash seems like a reaction to the Azithromycin and not std related. You should go see a doctor about the rash. Another advice is that don't quickly jump into conclusions based on google images, you should consult your physician for any medical issues.
more likely it's a drug reaction than it is signs of an hiv infection.
have you seen your provider yet?
also you already have a post going on the hiv forum - all hiv related questions should be asked there.
grace