Why is one of my cheeks bigger than the other? How can I fix this problem? (Photo)

I've noticed recently that My right cheek on my face is bigger than my left and I don't know why. My face has not always been like this, it use to be evenly proportioned. I thought it was my 2 dead teeth in the right side of my mouth making my cheek larger but I got that problem fixed and there's no change in my face. I don't know when or how this happened. I'm scared it will get bigger. How can I fix this problem? Why is my right cheek bigger than my left?