Ew, a cold sore!

Meg • First time Mama, Baby Girl Due February 14th 2016
I woke up with a nasty little cold sore in the corner of my mouth, I am 29 weeks- any baby safe remedies for this little bugger? 
I've already tried tea tree oil- BUT because it's on the crease of my mouth I want to be carful not to swallow anything harmful. Please help!