What happened to my lip?

Last night around 2 AM, to be specific, i noticed the left side of my bottom lip was getting all swollen; It felt like a big bump right under my jaw and up to the left side of my bottom lip, like if something had bit me, but then i noticed the bump was getting huge on my lip and this started to worry me because half of my bottom lip was all fat looking and the other side wasn't so anyways i decided to put some ice on it and thankfullly the swellen went down and eventually my lip returned back to normal a couple hours latter. Has this ever happened to you? Or do you know what could have caused this? This was the first time i ever experienced something like this and it was pretty scary. Now i figured it couldn't be a fever blister because those are on the inside of your lips and they don't feel like a huge bump. Second: i ruled out that it wasn't an allergy because i didn't eat anything out of the ordinary. Anyone know? I'd appreciate an answer. Thanks.