It can be due to dry skin, chafing or eczema skin. Do not use any cosmetic products at the sites. You can apply some calamine lotion at the rash as it will help in soothing the skin. Also wear cotton undergarments and apply plenty of moisturizers on the area. If the rash turns itchy then you need to get an evaluation done from a urologist and get fungal infections ruled out.
Many people do not develop symptoms after they first get infected with HIV. Others have a flu-like illness within several days to weeks after exposure to the virus. So it does not look like a HIV infection.
I hope it helps. Take care and regards.