Thanks everyone! He went to his doctor today. She put him back on Nexium and said they would go a scope and more tests if he was still having bad symptoms after that.
She also, in my opinion, hit right on the money in terms of his stress. He has been to the doctor at least once a week for the past 6 weeks for things that are mostly either triggered by stress/anxiety or the anxiety itself. He feels better already having just spoken to her and having her explain that the 'c' word is extremely unlikely and that his symptoms aren't even so bad compared to what a lot of people experience.
She said that she would be willing just to talk to him anytime if he needed someone to talk to or he could go to a psychologist.. she's a good doctor :)