U doesn't seems to have oral cancer, the thin layer you r talking about is The linea alba which is a horizontal streak on the inner surface of the cheek,level with the biting plane.It is prominent when ur back upper and lower tooth bite the cheek while chewing .Nothing to worry about that part
Apart from it if you have swelling on cheek , it is a point of concern as a picture will give a more clear idea about your problem
It may be the problem with the joints (TMJ), muscles of face , blockage in salivary gland(which secrete saliva ) , or problem with your wisdom teeth
Next Steps
Visit your dentist for proper clinical and radio graphical examination