Welcome to the forum.
Is the right side of your face swollen
Any other symptoms perhaps, like pain or tingling?
A tooth abscess or other dental issue may cause it. (Dentist)
If not, check for common food allergies. They can affect either side.
I used to react to eggplant in the past, and it always affected my right side.
Keep an eye out for peanuts and other nuts, shellfish, wheat,eggs,dairy,soy, as they are more common than other foods.