gastrointestinal neurosis
Medical term for functional gastrointestinal disorders with a psychological component; not a common everyday word.
I was diagnosed with gastrointestinal neurosis, but no organic abnormalities were found.
Irritable bowel syndrome (IBS) is a more specific diagnosis; 胃腸神経症 is a broader, somewhat older term for functional GI complaints linked to psychological factors.
Compound of 胃腸 (stomach and intestines) + 神経症 (neurosis). A straightforward medical compound.