I found plenty of sites where people asked the same question. Unfortunately, none of them got a definite answer.
One site suggested that you take a picture of the the blood on a used pad next to a red or orange background and show that to your doctor or gynecologist.
On another site, a person said this:
"Could be due to an elevated bilirubin count, which could be related to liver blockage or anemia. Bilirubin is an orange-yellow pigment contained by the bile formed as a breakdown product of haemoglobin. Excessive amounts within the blood produce a pale appearance. Yellow added to your red menstrual flow could result contained by ginger blood."
Keep in mind that this person may not have been a doctor.
Good luck in finding a solution to your problem. It's really fascinnating. I have never heard of orange blood.