Had brown discharge and stomach pains for a week now im having bright red blood and horrible pains on the Depo-Provera and havin unprotected sex. Whats wrong?

Get evaluation. It is not uncommon to have brown spotting or intermittent periods while on Depo, but with bright red blood, bad pains and unprotected sex, one needs to evaluate for pelvic inflammatory disease or possible spontaneous abortion, although pregnancy risk is generally low on Depo.