Why do I have a dent in my Forehead? (photos)

I started noticing a dent in my forehead above my right eye. This started approximately 2 years ago. It's almost like I pressed my thumb into my forehead and the mark never left. It was annoying at first but seems to be getting worse. I had a little botox injected awhile back, hoping it would help. I feel it's more prominent now and not sure if it's serious or just a random cosmetic issue. Please I am open to any suggestions.