Thanks for asking the query,
Cheek swelling can be a result of varios reasons, it can be due to the underlying dental issue causing inflammation in mouth, growth such as tumors, cysts, trauma to the face, allergic reactions and infections, inflammation of the lymph
node and parotid gland
known as parotitis
If a person is exposed to a particular allergen then the cheek may swell in response.
I would suggest you to get complete clinical examination by a Pedodontitis by taking necessary test and x-rays.
OPG radiograph may help in confirming the underlying cause.
Hope this answers your query,