Cyst / growth on lower lip suddenly appeared

Fighting winter cold and chapped lips, I recently noticed a bulge in my lower lip. It has swollen up pretty big and had a bit of pain to the touch. Happened suddenly. I am assuming its a mucus cyst but I am not entirely sure. Treatment has so far (18 hours since it appeared) been vaseline, salt water rinses and toothbrushing. Any informed advice would be appreciated. Not sure what to do.