Pain in heel & back of ankle. Tiredness.

Hi, I am experiencing pain since a long time in my left leg heel and back of ankle (marked pain area with finger in attachment. Also earlier the pain was more in heel but now have shifted more on back of ankle. Alos initially, the pain was in both leg heals but right one got cured when I started using hush puppies shooes. As recently checked my vitamin D level is quite low as 8. My earlier job profile was lots of standing for hours and current profile is lots of sitting. As recommended by doctor he suggest to keep legs in hot and cold water for simultaneously but it didn't give much of benefit and alos took medicines but problem still persist and worse in morning and whenever I am sitting for a long time. I go for swimming 3 days in week since last 1 year as excercise but stamina is not that great. I tried to walk or run but can't enjoy it due to this pain. During day time about 3pm I start to feel pain and heavyness in both upper and lower part of leg and little tiredness. Regards