Hi Welcome to Health care magic forum.
It appears that you have physiological dysmenorea, and it some times causes epi gastric pain some may have only epi gastric pain means near the stomach area.
In that case by eating the slate pencils, which are
calcium carbonate can relieve the epi gastric pain. It also may be the psychological relief also.
The causes for eating the slate pencils and other non food substances, is
anemia, and B complex defeciency.
I advise you to consult a physician for diagnosis and treatment.
I usually prescribe to my patient with such symptoms
albendazole, and Vitamin B complex.
Take more of green leafy vegetables, pulses, sprouts and
protein rich foods, to aid the treatment.
Wishing for a quick and complete recovery.