Could a diffuse, itchy, scarlatiniform itchy rash and pharingytis indicate primary hiv infection? i have not had intercourse, just "dry humping" with my girlfriend.

No!: I don't think so! you have to have mucosal contact to get infected with hiv. Of course intravenous drug users can get iy by sharing needles. But what you describe could be a disease we rarely see scarlet fever although is is mainly in young children. Go see a doctor to rule out strep throat... Also the rash could be of diagnostic importance. Go see an md!