hi i had gone through your query and understand your concerns. i would come up with two possibilities to fit your husband condition .these include
1.the first one include,ALLERGY
;is the underlying for the development of his complaints.
-Allergies are defense system over-developed by the body to give warning that its metabolic system is unable to handle a substance in a normal manner.
-unable to handle stress
-candida infection are some causes
2.the second possibility include,FLATULENT DYSPEPSIA
or ACID PEPSIC DYSPEPSIA.
-this condition also produced by unable handle stress
-suppressed strong emotions like anger,worry etc have caused the inflammations they will not get better until these feelings have come out into the open.
-taking too much pain killers are some causes
I hope this is helpful for you, thank you