What Could Cause Food To Come Up With Burps For One And Half Years?

Hii, my brother age 22 got a weird illness since last 1 and half years. After eating a food with 5 to 10 burps kind of thing food comes out of his stomach with every burp. We tried everything but docts are unable to track the disease. We did Evey test but reports are clear. Please suggest some solution.