Hi, Thanks for posting in HCM. I understand your concern. Hard and painful lump occurring after drawing of blood at the elbow is due to local infection and/or allergic reaction called thrombophlebitis . You need to apply ice packs on it to reduce pain and swelling. Take antiinflammatory analgesic Tablet. Ibuprogen with Paracetamol combination twice a day after food for 5 days. Also apply Ointment. Heparin Sodium (Thrombophob Gel) twice daily as a thin layer smeared on the affected area of the skin and leave uncovered to air dry. There is no need to rub or massage the gel into the skin. Always wash your hands well with soap before and after applying the gel. You should get better in a week time. All the best.