Running a cotton swab over the skin.
Terri
If this just came up, I would suggest that you go to a clinician and have this swabbed to determine the cause, since you have had it more than once in the same location. Generally speaking, herpes simplex virus type 1 shows up on the edge of the lip, nose or chin. It forms a water blister or group of water blisters first, that then break open and form a crust and that goes away in a week or two.
But the best way to find out about this lesion specifically is to get a swab test done, preferrably a PCR swab test, but this needs to be done early on, the sooner the better.
Terri
Also what does the test involve?