I Am Having Pain In My Back Especially On My

I am having pain in my back especially on my right side, I am also type 2 diabetic, I have being taking fultium-D3 800 IU capsules 2 per day for about a year, I have had a recent blood test and my doctor has passed a message on to reduce my fultium to 1 per day, could this be b ecause my calcium levels are too high and perhaps now causing me pain. Many Thanks Andrew Caton a 65 year old male.