Thanks for asking the query,
Swelling in the cheek can be result of various reasons, infected tooth may become abscessed and lead to pain and swelling of cheek, allergic reactions, viral infections, damage by some type of trauma, growth such as tumors and cysts.
I would suggest you to get a complete clinical evaluation by the Dentist
and take an OPG x-ray.
Get the x-ray of the molar done, get the abscess drained by the Dentist and get root canal
procedure of the tooth completed.
Take tab amoxiclav
625 mg twice, tab zerodol
twic for 5 days.
Use saline water gargles 3-4 times a day, use antiseptic mouthwash gargles twice daily.
Hope this helps out.