Hiatal hernia, usually, manifests as a heartburn, and is related to condition known as GERD.
Sometimes, anxiety symptoms can be attributed to the presence of hiatus hernia.
Also, is well known that people with anxiety are at greater risk from developing acid reflux.
Acctually, both conditions fuel each other.
Any kind of pain is experienced as a more intensive by an anxiety person.
On the other side, having hiatal hernia symptoms makes the anxiety worse.
Probably, his anxiety meds aren't helpful and he may need to take meds for symptoms of hiatal hernia, too.

Best wishes!
Marija