Had sores before
makes tiny blisters, in a cluster, very close together. Herpes blisters (vesicles) break open with some clear or yellowish fluid.
The sores are painful when touched, until they heal up. One can go to a doctor if such sores occur, to get a diagnosis made. If one doesn't remember ever having such sores, a blood test can tell if he has had herpes types 1 and 2.