Immediate onset of symptoms can never be due to infection -- thus no
STD is a possible explanation of your
lip burning etc. All infections require time for the causative bacteria, virus etc to invade the tissues, reproduce itself, and induce an inflammatory response by white blood cells, the immune system, etc. That process always requires at least 1-2 days, often several days or longer. Such immediate onset like you describe has to be due to either a physical injury (e.g.