I Just Started Using NuvaRing For Birth Control Last Month.

I just started using NuvaRing for birth control last month. I took it out about 2 days ago and I'm currently on my period. Tonight, I noticed a long fleshy looking piece of tissue/discharge come out of me. This has never happened before and I'm a little nervous about it. any ideas as to what this is that came out of me? Maybe the lining of my uterus?