it is not possible to determine the nature of a rash based on a vague description so you will need to see a medical provider so you can have this all-over rash properly examined diagnosed and treated. since you are concerned that this could be a consequence of unprotected sex seeing a medical provider is even more important. if necessary the medical provider can test you for hiv and other sexually-transmitted diseases.
a rash is appearing all over my body. started upper arms then back now penis concerned because i had unprotected sex. concerned about hiv