What do you think this is??

HI just wondering what you mama's think of the rash/blisters that appeared on my 2 yr Olds upper lip! At first I thought it was swollen and a mild allergic reaction but there wasn't any other symptoms of distress. It's been there for 2 days now. Do you think I should take him to the clinic? I'm worried one of his aunts kissed him on the lips and maybe gave him herpes 😲 but also they aren't like open blisters so they are likely due to the cold weather making his lips dry and causing him to lick them too much making a rash. What do you think?

You can see a bit on his lower lip now too which makes me also believe it's from licking