Hello, What was the history for removal of the jaw is very important if it was removed for a cancerous lesion and if their is a swelling may be they are suggesting for recurrence or  if it was due to any road trauma and accident it may  be  graft failure which is causing infection and swelling of the jaw . Other things to be noted will be do you have pain in the swelling, tenderness, temperature of the swelling etc. You will have to consult a dentist and get and scan done and get it checked properly.