Eric,
Food IgG (finger prick test) – from Great Plains
H. pylori antigen (#418) – from BioHealth Laboratory
I would start with these. If nothing, than go after the OAT
from Great Plains.
Sounds like this fellow needs to implement some type of irritable bowel disease, like the SIBO diet – http://www.siboinfo.com. This would likely help.
Dr. Woeller