This could be due to dermatitis or eczema, folliculitis or other skin conditions. Are there other signs or symptoms present? The window period of HIV vary since it can take 3–6 months to seroconvert and to test positive. Detection of the virus using polymerase chain reaction during this period is possible, and positive results obtained by PCR are confirmed by antibody tests.
It would help if you have these rash evaluated further by a dermatologist. Diagnosis is through a complete physical examination and testing the lesions. This will help in reaching a clinical diagnosis. Take care and regards.