Hi. I have been in a monogamous relationship for two years. My boyfriend has had cold sores (start as grouped blisters on the lip/ corner of lip which rupture and heal over a short period of time). After engaging in oral sex I developed similar grouped blisters that spread over my vagina with burning urine. I was convinced he had given me herpes, however he has now had himself tested and all the tests have come back negative (including a IgG). He is now questioning my fidelity and I've honestly only been with him. Is it possible to have a false negative IgG and if so, what is the likelihood? Is there something else that could have caused this?