Actually, a long trunk and a narrow pelvis (common in men) can make for a very difficult j-pouch procedure because of the physical "reach" of the blood and nerve supply for the small intestines. It can even lead to an inability to do the procedure.
That said, years after surgery, he should have been able to adapt and function, as long as there was not chronic ischemia (reduced blood supply) to the anastomosis because of the "iffy" surgical presentation. Chronic ischemia can lead to functional difficulties, along with inflammation.
In addition, it does sound like he has other autoimmune troubles with the joint pain and eczema. I would suggest he be evaluated by a rheumatologist. If he is on medications for high blood pressure, that may be contributing to his other symptoms of weakness, fatigue, and dizziness. Sometimes, the medication is the root of many ills, so it important for ALL of the doctors to work together and make sure that he is treated as a whole person, not individual diagnoses.
A rheumatologist is a good person for this, as in addition to being expert in rheumatologic diseases, he would also be certified in internal medicine, and be able to look at issues like drug interactions.
Jan