It's probably the nuvaring. I had a lot of brown spotting for the first couple of months. And IF you did it so you wouldn't have a period you probably just have some break thru bleeding going on. Just start taking it the normal way, it may take a month or 2 to go back to normal.
In theory, as long as you put in a new ring on schedule (when you were supposed to take the last one out), you are probably fine. However, to ease your mind, I suggest taking a pregnancy test - just a cheap over the counter one. I keep an extra one around, just in case I have a scare and want to know right away.
My sister and I both are on Nuva Ring. I use mine as suggested, but my sister who has two children thought it would be a good idea to try and skip. I am in Pharmacy, and I would have to say with Nuva Ring you should not skip. Also, according to my sister DR she said the same thing. She was bleeding for 2 months straight.