Thanks for posting your query.
Herpes genitalis is caused by Type II herpes simplex
This same virus may also cause herpes labialis (as in your case). Herpes labialis is caused by both Type I & II herpes simplex virus.
This virus remains in dormant condition in nerves of affected skin area which may get activated when there is breach in immune system.
You should consult with internal medicine specialist/ dermatologist
and should go for proper treatment.
You should also take antiviral
medications both oral tablets and topical application.