Calcium, magnesium and zinc with D is tearing up my stomach????

Just started taking this with the D in it and have been so cramped up and constipated, especially at night when I am trying to go to bed!!! UGh.. the next day I can usually go but by evening I feel crampy and constipated again. Could it be the D in the vitamin I am taking? I am usually loose as a goose but this is worse, I will take loose any day over this.