For a few days before the period is about to come, there is always something reddish-brown at the bottom. Why is that?

Patient's question:

Married
These past few months, every time a few days before my period, there's a reddish-brown substance discharge. It feels like my period is coming, but it takes about three days for it to officially start. I don't know why this is happening? Is it normal? I had a vaginal discharge test done in the first half of this year, and the results were normal. Please help me, doctors. Thank you
Additional information: This condition usually lasts for two to three days, similar to the amount of leukorrhea, but the color is reddish-brown. After two or three days, my period starts officially. My normal period lasts six to seven days, and the amount is normal, but I do have menstrual cramps.

Doctor's answer:

Your condition still falls under the symptoms of certain gynecological inflammation infection, so it is recommended to actively go to the hospital for an ultrasound examination to determine the specific treatment and medication.