I have suffered from this all my life and thought it was normal, until I heard it mentioned on some programme or other. It is far more prevalent than CH but still relatively rare. I would be interested to note how many sufferers here also have this condition. One red flag for a link to CH is that a suspected cause of EHS is temporary calcium channel dysfunction. Calcium channel blockers have been used to try and treat EHS, I am not sure how successfully.
More information : https://en.wikipedia.org/wiki/Exploding_head_syndrome