The only ways adults (I'm sure you've heard this before) get HIV is from unprotected vaginal or anal penetrating intercourse or sharing IV drug needles. Oral sex does not transmit the virus because saliva and air inactivate it. So, you had zero risk. You can get a rash looked at and I would do so, but it is not HIV related.
You had no risk from what you have described. Therefore,I suggest you find a dermatologist and change your laundry detergent and/or the soap you're using in the shower because this has nothing to do with HIV.
What and when was your exposure?