A rash can have several reasons including those that you have mentioned. However the cause of the rash can be deciphered only once it's examined. So see a qualified dermatologist near you or send in the photos and details of the rash on follow up chat. Chances of
hiv transmission are absent if the blade was new and if it was used only for you. Warm regards, Dr Govind Suresh Mittal, Bengaluru.