I have been suffering from a constant headache now for over 1 month.  It is one headache that started in March and has not stopped yet.  I wake up with it and go to sleep with it.  I am unable to work as it is so hard to do anything when your head is constantly in pain.  Anyway, I was speaking with one of my employer reps from the employee program and she informed me that a guy just a few weeks ago that she worked with was diagnosed with "New Daily Persistent Headache.."   I haven't yet researched it much but there are many links online when I do a search for that title.  Maybe this is something that may be of help to your grandfather.  Good luck to both of us.  Deniese