I got a blister last week that grew to be large and puffy. Doesnt look like small vesicles, doesnt itch. I drained it and it was an opaque color. No blood.
http://i65.tinypic.com/w7c6yv.jpg
http://i64.tinypic.com/2m7f4n6.jpg
Im really paranoid and just dont remember burning myself or anything to get a blister. I get cold sores but like years apart since a child.