She is sick and so grouchy! Of course I would be, too, if I had blisters in my mouth. This sounds so nasty, because what it is, is never what people first think of when they hear it. She has a herpes infection in her mouth. Herpes Simplex 1, Oral herpes, meaning cold sores. The primary infection either has no symptoms or blisters in the mouth. My baby girl was so lucky enough to get the blisters. She has at least 5. She can't eat, barely drink, and is so not sleeping well. She wakes up several times a night whining. There isn't much I can do for her and there isn't really anything she wants to do. She went swimming at Grandma's and spent half her time there crying. Poor baby.