Stopped Birth Control Pills. Had A D&C. Whitish Vaginal Discharge, Back Pain. Taking Flagyl. Pregnant?

Hi, im 26 years old and recently had a d/c 2months ago, i also recently stopped taking birthcontrol pills after ten years. Since that surgery ive been having watery, sometimes milk colored CM gushing from my vagina . My doctor initially prescribed me flagyl . However the discharge continues. Ive already had a period this month and have taken 2pregnancy test which were negative. Recently the discharge went from light yellow to light brown, almost as if im spotting, and i have cramps and slight lower back pain ...Im praying that im not pregnant, what else could these symptoms indicate??