What Causes Delay In Menstruation Other Than Pregnancy?

hey i have not had my period for 5 months, i had a little dark blood for 2 days and bad stomach cramps...there is absolutely no way i am pregnant.
i eat very healthy but i keep binge eating at night time, i can go 2 days or so without it but i keep spiraling back and doing it all over again.

Do you think this is the problem?