 [ Symptoms ] ive been experiencing constant burn sensation on my mouth it affects my tongue lips [ Disease ] 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