Given your symptoms and your concerns about transmission to your son, I think it would be a good idea for you to get a herpes western blot. The herpes Western blot is more sensitive for HSV 1than is the screening test that you took. I think the dermatologist is correct in that it is possible to be infected and have the herpes medicine partially suppress herpes symptoms. If you could determine from Western blot that you did not have HSV !, would this help relieve your concerns about the itching? We do know that the antiviral medicines are slightly more effective against HSV-2 then HSV 1. If you were my patient at my clinic I probably would recommend that you get this test to help clarify the picture or put your mind at rest. If the test is positive for HSV 1 then I think the next step would be to PCR swab the symptoms that you are describing. As you may know, just because you are infected with HSV 1 not everything on your lips necessarily is caused by herpes.
Terri