Possible cold sore on 3 yr old

[Bananamama1213]

My daughter has what looks like a cold sore.

My 10 year old sister has a nasty one at the minute (but she is always very careful with it and any bottles etc that she uses). She's very mature with them.

She says it hurts but is happily eating ready salted crisps. I've given her mouth a wash and put the flannel in the machine, washed her hands with anti bac soap.

She does eat a lot of ready salted crisps - hoping she's had too much salt and it's hurt her lip!

I feel so guilty, like it's my fault