Notice this at 1800hrs when going to bath my 21 month old daughter. Seems like blood.

May I suggest you consult your PD? For cases like Poo with blood stain/red steaks are due to Viral/Bacteria infections and since she is not infant I believe there are medications to cure unlike infants which may be worrying for you. If you have concern, I suggest going through polyclinic for referral while you monitoring the flows of blood to see if it’s persistent or increasing before deciding to rush to hospital. Be calm.