Hi, The swelling you have is called a 'mucocele'. There are minor Salivary glands that produce saliva in the lip. Mucocele occurs when the gland is constantly irritated or if the duct of the gland is blocked mostly due to lip biting. It is harmless. The permanent treatment involves a minor surgical procedure that involves excising the mucocele with the minor gland. It is a simple procedure done under local anesthesia that would take 15-20 minutes. 2-3 stitches will be put post procedure that will be removed in a week.

mucocele . Its called as mucocele. It's not cancer . And it's not ulcer. It's a cyst. Go to a dentist. Preferably an oral surgeon. And get it removed. It usually occurs due to sharp tooth edge or due to trauma (hit)