Hi welcome to Health care magic forum.
As you describe you had a swelling on the left cheek around the mouth, family doctor, E.N.T.surgeon, could not find any fault.
If pain is there it could be secondary to the dental abscess
, which will be deep, and appear as a swelling in the cheek. The dentist will have an xray and confirm the diagnosis.
If there is no pain it could be an allergy
to some drugs, or some other allergen.
I advise you to consult a dentist
for confirmation . You may have to get an intraoral x ray
Wishing for a quick recovery, and thanks for calling H.C.M.F.