Hello,
Sometimes an infection can cause menstrual blood to look and smell funny. If associated with a foul odor (remember blood itself often has a characteristic smell), tenderness or fever, this should definitely prompt a visit to the gynecologist. Commercial pad such as Always or Kotex are made from synthetic materials and plastics, these prevent aeration to your vulva so get your groin hot and sweaty, as ably as mortified this give the sound environment for germs and yeast to multiply. Menstrual blood does not smell, the germ that multiply in the blood is what is causes the smell.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
You may have a bacterial infection, which is normal. It causes smell and discharge issues in our bodies. Go to a planned parenthood clinic for a walk-in or make a phone call. Easy to clear up with treatment.