What Causes Spotting With No Regular Menstrual Flow?

Im 8 days late for my period. I had a tubal 10 years ago during a c-section.... No problems other than slight naseau until yesterday. Called my dr and made appt for next Tues since little was wrong. Last night I started to spot (very little and faint pink). Today Im having lower back pain, tightness in abdominal area, and just recently the spotting is becoming bright red. Still no reg blood flow. Its only when I wipe. I thought at first maybe I was just starting period late (which has never happend except when I was pregnant), but the brightness along with everything else makes me concerned. Should I call dr immediately or wait and see how the rest of today goes and call tomorrow if things worsen?