Has there been a traumatic / stressful event in his life recently? You mentioned after his father had died he'd suffered the same symptoms, this sounds anxiety related. Particularly as in the morning he has no problems, anxiety (in my experience and I have LOTS of it) doesn't really rear its ugly head in the morning, it takes a good few hours for your body to wake up and start worrying.
I had throat problems with anxiety in my teens, as did my uncle who could afford private consulations which was what was needed for a physician to take the problem seriously and seek a diagnosis. It was eventually diagnosed as a harmless condition called Globus. Net search this to see if its similar to your friends affliction.
All the best