I have started taking calcium supplements with vitamin d in the past month and i have developed very bad breath. is the bad breath a side effect.?

Probably not: I would suggest you start by seeing your dentist. Usually bad breath is from oral bacteria. If the dentist finds nothing wrong, i would see your physician because it could be something else.

Should not be: The supplements themselves should not be causing the bad breath unless you are burping from them which could cause the foul odor.