Did you know that taking calcium supplements together with Vitamin C supplements can lead to kidney stones?
The most common form of kidney stones are formed from Calcium Oxalate. "Vitamin C: When vitamin C is used by the body, oxalate is produced. Therefore, if the physician has recommended reducing oxalate in the diet, taking vitamin C supplements may not be a good idea. It should be discussed with the physician. " -http://www.gicare.com/Diets/Kidney-Stone.aspx
This can cause problems worse than pain. For example, a stone can become large enough to obstruct an entire kidney, causing kidney failure on that side. This can go on for years unnoticed, as just happened to someone I know.