What Causes Vaginal Bleeding While On Nuvaring?

I started the nuvaring January 29th. The day before I was due to change the ring I started to lightly bleed. My doctor recommended that I used 3 rings in a row and then remove for a week to have my period. So on feb 10th I removed and replaced a new ring. The bleeding however hasn t stopped and it s been over a week. Should I remove the ring now or wait until the 3 week cycle is over?