So I have a dent in my head...?!

So I have a dent in my head...?

I know this is going to sound crazy, but a few months ago I was rubbing the back of my head and realized there is a rather large 'dent' at the top / back of my skull. I know it is a relatively new thing, and I haven't suffered any blows to the head. It's not just flat from laying on it, and where it's positioned it can't be from laying on it too long or wearing a hat. I'm not having any health problems and don't want to go to the Dr. because i'm afraid they will just laugh at me. Is there something that would cause this other taking a severe bump to the head? Thanks

I'll be damned. I have a lump in the same place.
I don't remember bumping into you.