Hello, As the symptoms you mentioned this appear to be related to venous return. Before this, I would like to ask you if you have any Diabetes or high blood pressure issue. If so please kindly get it checked and monitored by a physician. Next, this bluish or blackish or purplish discolouration is due to something called varicose veins. You need to meet up a vascular surgeon and get a doppler scan done so we can some inputs if that is the one. There might be a possibility that you may be put under some medication for the same. You can use hot water fermentation and do the maximum exercise of the calf muscle like ankle toe movement s keeping the leg over the pillow. Pain will subside with painkillers but we shouldn t ignore the varicose veins as this may later stage give more trouble if left unnoticed. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Jay Indravadan Patel, Physical Therapist or Physiotherapist