Hook already explained why this is not an HIV rash
. In addition, heterosexually transmitted HIV
remains rare in Sweden, especially in Swedish nationals; heterosexually transmitted HIV in your country is largely limited to immigrant populations from Africa, eastern Europe, etc. And you obviously understand, intellectually if not emotionally, that you are not at risk.
I agree that a rash that comes and goes so quickly is probably hives, i.e. an allerfic reaction to something.