Been on my period for 4 weeks now?

I had a baby almost four months ago. I started a birth control pill at 4 weeks postpartum, they gave me migraines and made me have horrible break through bleeding. I went to the doc she switched me to nuvaring which was awesome the first month I stopped my break through bleeding as soon as I put it in. I was on it the first month and it was great for the most part. Then I had a check up on a thursday, my 4 weeks on the nuvaring was up on that tues so I took it out. (My doc told me I could use it for four weeks to not have a period thats what she does.) well I started my period because I had to take it out because my appt wasnt until two days after the four weeks was up. Now I have not stopped and it has been four weeks its mostly spotting sometimes gets a little heavier. Has anybody ever experienced this?