Do they always appear in the same place/under the same circumstances/look the same/run the same course?
I have had two coldsores (I think) in my life, both under my nose, appearing after a heavy cold with lots of tissue scrubbing action, both blistered in 24 hours, second responded to Zovirax (didn't try it for the first as really register it was a coldsore).
Now I have a sore red "spot" on my lip - it's more a hard lump than a raw patch. No cold in sight, no blisters since it appeared on Saturday but am using Zovirax anyway. Could this be a new manifestation of a coldsore?