My 25 year old partner has today had a cold sore appear. I have a one year old and have told him not to kiss him or share anything of his. Neither of us have any suffered from cold sores before. How worried should i be about my son. We came back off holiday last week from Crete and whilst there i had a really sore upper mouth which made it really hard for me to eat or drink as it was so sore, could this of been the start of something and i have passed it to my partner? i have had no cold sores?