This morning I woke up with a sensation of numbness to my left jaw. I do feel a bump if I touch my jaw. On the mirror I can see the area swollen. Why?

Get to a dentist!! I would have a radiograph taken of the area in question, a panoramic radiograph would be helpful to make sure there isnt any gross pathology or a wisdom tooth problem, a periapical radiograph can zero in on a particular tooth...Your dentist will know which one or if both is necessary, do not delay go in!