I have a horrible odor coming from my vagina. i am not sexually active. and have irregular periods. it smells like period and i get light brown discha?

Vaginal odor: Assuming you are not sexually active which you stated, the most common reason may be a lost tampon, you need to check then see a physician.

See your doctor: First, i doubt anything truly harmful or dangerous is going on. Second it is not normal for most women to describe discharge so powefully, so you really should see a doctor soon to have this checked out.