Hello! I have some calcium powder (no phosphorous with D3) for my garter snake, but I think it may be "off". It has a fishy smell and I noticed when I apply it to fish (tilapia) it creates small red specks that kind of worry me a little, since I didn't remember it leaving them before.

Is this normal or has it gone bad?
Does calcium expire? How often should I replace it?

(Also, hello! I haven't posted here since 2010 but I still have my same snake, Tiberius. She's about five years old now.)