Goldgato
I don't know if I could call it wrong. It's not common at least. I think most people would consider consumption of human blood cannibalism, though as long as it's consensual and doesn't result in significant harm I wouldn't call it a wrong practice.
Consuming blood isn't cannibalism.Cannibalism specifically refers to eating the flesh of another human, not drinking their blood.
Craving blood is probably a result of some kind of vitamin deficiency. I wouldn't just assume it's a mental disorder, and it's certainly not wrong to have cravings, but I probably would see a doctor about it.