Calcium deficiency does not usually show as swollen lips in chams. Most likely it is an infection either from injury to the lip or gum or from a systemic bacterial infection. The term "mouth rot" or stomatitis is a result of bacterial infection not a cause in itself. Look closely at your cham's mouth for reddened areas, patches of cheesy material in the mouth and throat, and obvious pain around the mouth or under the skin on the face.
Just an observation for list members:
Lately, for some reason "calcium deficiency" or MBD seems to be the "ailment of choice" for folks on this forum. It is being blamed for an amazing array of health problems. Maybe because it has been discussed so much recently. It is only one of a group of nutritional problems we could see in captive chams. We need to remind ourselves to look outside the box when trying to diagnose and treat cham illnesses.