Okay, so I am having the worst craving since the beginning of my 3rd trimester. It won't go away. I…

Okay, so I am having the worst craving since the beginning of my 3rd trimester. It won't go away. I am craving chalk. I'm currently 37 weeks today,but the craving is so strong it just won't go away on its own. I've tried smarties and tums..but I still crave that chalky flavor. Any tips?