6mo has developed cold sore - can anyone reassure?

[OnThisHarvestMoon]

My 6mo has developed a cold sore and I’m beside myself with worry. I really don’t know how it happened as we’re aware of the dangers and have never let anyone with an active cold sore kiss her/hold her. However, the gp I spoke to today did say it was possible for carriers of the virus to shed it even if they don’t have a cold sore/haven’t had one recently, and we do have a few family members prone to cold sores, so it’s possible she got it that way.

We’ve consulted with two gps and they’ve essentially said to do nothing except watch and wait to see if she becomes otherwise ill. (So far no symptoms beyond the cold sore itself). 

Just wondering if anyone has experienced similar and has any advice? I’m so anxious I’m unable to sleep.

Thanks so much