What Causes Swelling In The Lower Lip?

My right lower lip started swelling last night, then spread to my right upper. i decided i couldn't do anything about it so late and went to sleep. when i woke up this morning, both lips were so swollen i couldn't even fully close my mouth. throughout the day, it has progressed to the left side of my upper lip, but now the bottom lip and right upper are normal. it's like there's a caterpillar crawling around inside my lips! have you ever heard of a swelling that moves like this?