Does my baby need immediate help?

I’m currently at a family gathering & my boyfriends mom was hold our daughter. I wasn’t even paying any attention until I heard her kissing her on the forehead. I then noticed she has a HUGE blistered cold sore. When something was said about it, she swears up & down that it’s dried up but she’s been picking at it & it’s now bleeding. I’m freaking out. My daughter is three months old. Do I need to call her doctor? Please comment below. I’m limited on my information with babies and cold sores