dd 12 months developed a blister on her lip today. She also has a temperature. Neither dh nor I nor ds has ever had a cold sore. She was kissed quite sloppily sunday night by a toddler whose mother gets cold sores, though i didn't notice them having any at the time. Could this be the source? Should i take her to the gp? She is breastfeeding and if I get one on my breast that will be awful. Is there anything else it could be, so worried for her.