Is This An Allergic Reaction?

Okay, so about a week ago the skin around my mouth started getting really dry. I thought it just needed some moisturizer. A couple days later it started to get some minor swelling and felt like there were little tiny blisters all around my mouth. So i started putting hydro-cortisone on it and it stung but helped a little with the swelling. Under my bottom lip it was very itchy and after scratching it a couple times throughout the day it looked like a hive appeared under my lip. I dont think it's herpes because i have been kissing the same guy for almost three years and he doesn't have anything like that. But i began to become concerned when i realized my dad might have it and he possible took a drink out of my two liter of pop before i drank out of it. But the little bump doesn't look like the beginning of herpes at all. Any ideas if this is an allergic reaction?