I have this small defect is mostly above my upper lip, but it starts at the lip. It resembles a regular grain, alone, is painful and comes back once a year, which lasts a few days before disappearing again.

If it is a cold sore, what could have caused?
I mean, I have looked online possible causes and none of them seem relevant to this case.I'm not sick, I've never kissed anyone, I'm not suffering from stress, etc.

Solution:

since it starts * in * the lip, it is very likely to have cold sores. although I've never kissed anyone with a passion, the # 1 way cold sores is transmitted through a kiss on the lips "by a relative, and usually at a very young age. for example, "Aunt Jane" (which sometimes gets cold sores) kisses his baby niece … and the baby to grow with cold sores, not knowing how obtained …

however, the same scenario that could occur at any age … For example, Aunt Jane kissing his nephew on the lips too – but never had cold sores as a child … however, only recently developed, though never kissed anyone with passion … but Aunt Jane had been visiting the previous week and had given him a kiss on the lips.

(Via Y!)