My head apparently has a ridge or deformity at my hair line just above my forehead.... discovered years ago after wearing any properly fitted helmet for any length of time a pain which became so intense as to have me strapping my hat on the back of my bike and riding sans protection.
Yesterday I got so fed up with my latest headache that I grabbed my helmet and headed to the garage. Putting the helmet against my leg, holding the straps out of the way, I took a hammer and firmly pounded the foam down a bit right where the pain originates. Tried it on and quickly realized I was on to something!! Tweaked it a bit more and viola!!
As I type this I'm near shedding tears of joy at the thought of putting that once torturous iron maiden back on my irregularly shaped dome.
I hope this helps somebody half as much it helped me.