That is very harmful for you and baby. Please dont eat it.
Your doctor should check you for vitamin deficiencies. That way he or she can prescribe the right diet/vitamin to make it stop. Please don't eat it.
definitly tell your dr. I'm pretty sure that means your body is not getting enough of a certain mineral.
You need to talk to your doctor about that. I think they call it pica or something and its when you crave things that aren't edible it's very bad for you and the baby.