I'm A 32 Year Old Female, I Suffer From Chronic

I'm a 32 year old female, I suffer from chronic migraines with allodynia. About 4 months ago I noticed two very large and deep dents formed on my skull behind my ears. They're very tender and painful. Approximately three weeks after I noticed them, the one on the left side filled back in, at times a smaller dent comes back. The right side stays pretty deep and large, but the size does change as well. I have had a CT of my brain which was normal. What could these dents possibly be?