One side of my cheek is significantly thinner than the other side, why is that? The layer of the skin feels much thinner...

My cheeks were very even before, but since the past 2 years or so, my cheeks have been starting to become even more asymmetrical. It's definitely not the "normal" kind of asymmetry a person might have, there is a difference in the skin or muscle itself on the cheeks for sure. I have tried chewing on my right side for a while (thinner side) but it hasn't solved the problem. When I use my tongue to push out on the cheeks, my left is much harder to push out than my right. Right side is VERY thin.