Is this a generalized swelling of one half of the lip or is there a nodule like swelling???? The verbal description mentioned by you is not sufficient to arrive at a rational diagnosis. A clinical picture would be a better tool. Alternative way you can post the clinical photograph on Practo for an online consultation with a specialist. Absence of pain does not always undermine the gravity of the situation, so a proper diagnosis followed by the appropriate treatment would definitely be recommended as soon as possible. Regards.