Given your age, colon cancer history, and that your right kidney is functioning at only 10%, you should not take Sharkoferrol or any iron supplement without a doctor’s advice, especially since your hemoglobin is normal. Mild shoulder weakness and occasional hand discomfort are likely related to muscle weakness or posture, not iron deficiency. Focus on balanced nutrition, adequate protein, gentle strength exercises, and regular check-ups with your doctor and nephrologist to keep your kidney and overall health monitored, and discuss any new symptoms before starting any supplements or medications.