Hi! You have not mentioned if you have got fever
or not. With fever, it could be a pelvic inflammatory disease
in which you may get such discharge with foul smell of which there is no mention in your history.
The second possibility is that you might have got a miscarriage
with an undiagnosed pregnancy
You have not mentioned about your age. In relatively older age groups with repeated deliveries, we may expect some kind of prolapse of genital organs in which one may get lower abdominal pressure along with a reddish brown discharge.
You should consult your gynaecologist and get yourself examined, who may advise you for an ultrasound
abdomen along with a routine urine test, a urine pregnancy test, and a serum HCG. I hope this suggestion will help you. Good luck.