My 18 Year Old Granddaughter Has Been Taking A Zpack

My 18 year old granddaughter has been taking a Zpack for a severe cold/sinus infection and bronchitis. Those symptoms are much improved, but 2 days ago she started getting a swelling in her jaw area and now she looks like she has the mumps( She was immunized as a child). She has a significant amount of pain and is miserable. i can't get her a Drs appt until tomorrow, they have no openings. What else would cause this type of swelling.