herpes simplex
"I was in Mexico and spent the whole day drinking at the pool (I think they did not wash glasses properly and I contracted it there). I went for dinner and just as I finished my meal I licked my lips and right away could feel the tingle, then bit my bottom lip where it was and had that very sharp pain. Could tell right away, having had several when I was younger. A single small blister had formed on my lip already and luckily I carry Abreva everywhere so I put some of that on right away. Next day it had "popped", I soaked that and put more Abreva. Was starting to heal and crust within 2 days. This is why the ladies in my family carry it everywhere. You have to use it straight away to stop the spreading, but its a life saver."