Hello,
Welcome to the ehealthforum and I am really glad to help you out.
Having fatigue after gall bladder disease and pancreatitis is common and the other reason can be anemia causing these symptoms. Eat a healthy, nutritious diet, try having uninterrupted sleep of 8 hours a day and take some iron supplements for some days. If the symptoms persist then please get it evaluated from a physician.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.