Hello Welcome to health care magic. Discolouration at ankles with swelling and pain is due to deep vein insufficiency or thrombosis and not due to sunburn. If I were your treating doctor,I would recommend, -Get colour doppler of peripheral blood flow of legs.You may visit vascular/general surgeon for it. -Low dose aspirin may be started as prophylaxis against thrombosis. -Apply compression bandage,sit or sleep with leg elevation of atleast 10 cm.All these will reduce pain and swelling.Check the lower leg area if any ulcer develops. -Avoid standing at one place for long time.Do frequent ankle movements like flexion,extension ,rotation. -Avoid smoking Keep an eye on symptoms like sudden onset of chest pain,breathing difficulty or chest pain and report immediately to your physician if it happens. Hope this information helps. Wish you good health.