L.C.
Hi C.,
If he stresses over everything then he could have an anxiety disorder. Anxiety disorders are often accompanied by stomach problems because the stress and worry cause excess stomach acid.
There are lots of things that could help him. If you can actually get him to do it, yoga can be very relaxing and allow for a physical release for the anxiety. Finding a counselor who can help him learn to recognize triggers for his anxiety, analyze his feelings and responses to triggers so he can head anxiety off at the pass, and de-escalate his anxiety and manage his stress is another really good thing. A psychiatrist that can prescribe anti-anxiety medications might be helpful too in addition to these other options.
L.