Welcome to HealthcareMagic. The cause of such dark and dry periods can be hormonal imbalance, stress, anxiety, eating disorder
or medical causes like polycystic ovarian disease
, thyroid gland disorders or diseases, pituitary gland
tumors or cyst etc.
If this was the first episode of irregularity in the periods, then wait for the coming cycle and try lifestyle modification by reducing stress and decreasing cholesterol
levels. But if the repeat happens, then please consult a gynecologist and get yourself thoroughly examined.
Hope it helps you. Regards.