Thanks for your query, I have gone through your query.
The possible causes for the limited mouth opening and the swelling over the face is
tooth infection with spread of infection to tissue spaces.
the other possible cause of the limited mouth opening could be because of the disc displacement without reduction in the jaw joint, but in this condition swelling will not be there.
the one more cause that causes both limited mouth opening and swelling is fractured jaw bone.
Consult a oral physician and take radiographs like OPG, TMJ views to rule out the above said causes.
If there is tooth infection then,you can take a course of antibiotics and analgesics like
amoxicillin 500mg and
metronidazole 400mg tid for 5 days (if you are not allergic).
Do saline gargling.
If it is
TMJ disorder then you have to take tablet piroxicam 20 mg twice daily on first day and once daily for next 6 days. do not take hard food, do not open your mouth too wide.
if it is a
bone fracture, then get it treated surgically by placing plates and screws.
I hope my answer will help you, take care.