Hi Dear User ! Thank you for posting your questions here . I would say that the cramps especially in the feet may be caused of your vitamine D deficiency .Low vitamine D means low calcium and cramps . You can put a firm pressure in your sternum or tybia if it s heart while you do that means that the pain comes from the muscles or bones due to hypocalcemia. Also using steroids one of the side effect is destroing the bones and cause pain. The pain also may be caused of your nerve damages .One of the complication of high blood sugar .You should keep the sugar level back to normal . I would suggest to measure the calcium levels , also some other examinations to find out the cause of low vitamine D , kidney, you intestine , liver , parathyroid glands , lack of sunlight , low vitamine diet. If you have done kidney and lives examinnations as You sad , the local doctor should search for the other cause...And if it s neccesay to start vitamine D suplement t reatement. Manwhile increase your vitamine D in your diet. Wish you good health. If you have any other questions please feel free to ask .