What Does It Mean When You Have Skin Discoloration?

Normally the skin discoloration occur when you have some deficiency of vitamin inside your body. The white spots appear on your body when you have deficiency of calcium in your body. But still I suggest you to consult your doctor for other symptoms and any medication.

Could be the uv rays of the sun if you have sensitive skin. Or it could be hypopigmentation depending on the state.

White spots on your fingernails indicate injury, or lack of zinc, in which case take chelated zinc supplements. White spots on the skin could be the start of vitiligo, a reduction of pigment. If this is it - be careful to use sun screen as your skin is losing it's natural protection.
There is normally very little calcium in either your skin, nor your nails, so it is nothing to do with calcium.