How Can I Stop Eating Chalk?

since i got into 7th month of my pregnancy i got the craving of eating slate chalk. the one which is thin and flat. and the addiction was so strong that after i delivered my baby i continued it and its been now almost two years. i use to eat 3 packets (each containing 20-25 chalk sticks) within a month or so. now suddenly i feel my digestion has been severely slowed down. i feel heaviness in my stomach as if foddd is not digested at all. i have tried a lot many times blackmailing myself on the name of my baby as well but i cant stop the craving of eating chalks. please help me docs