Hello I have gone through your question and understand your concern. I would suggest take up a complete urine examination along with along with urea and creatinin levels. Some kidney donors, later in life may lose their kidney function and may require dialysis in the future. To minimize the complications it is better to assess renal health even in apparently healthy donor, even after years. Pain can also be caused due to urinary tract infection, and can be treated easily with the help of antibiotics based on urine culture/sensitivity. Get the diagnostic test done and update your reports at HCM or consult your family physician. Good luck. Hope your concern is answered. Thank you.