Terrible oral sores - "apthous ulcers" - cause?

My husband has suffered from oral sores that look similar to herpes lesions in his mouth since he was a small child. Other people in his family suffer from the same problem but not like he does.

A few years ago he was hospitalized, they were so bad that he could not eat due to intense pain from the canker sores. The doctor gave him a herpes medicine to try and said if that did not clear up the sores, then the sores weren't herpes. The medicine did nothing for him. So apparently it is not herpes.

His "kissing partners" and previous sexual partners have not developed the canker sores. Neither have I.

His mouth is full of dozens of sores and he is in agony. He has been to many doctors.

Any thoughts about what the cause of these ulcers/canker sores might be? Any thoughts about how to help? He is miserable. Tweet