Three days ago I noticed a small bump on my upper lip , close to the centre. When I awoke on Sunday morning, my upper lip was swollen with one water filled blister on the head of the swelling . It was not painful but it itched a little. Have no idea what caused it, whether an allergy or bacteria. Have had a herpes break out about 14 - 15 years ago, but not since. Note: this swelling did not occur at the edge of my lip, but dead centre. Have applied an anitbiotic cream which caused the blister to leak out and there was no color to the liquid. Today, the swelling has gone down significantly but the blister patch is drying away. Are you able to identify what this is?