Spotting Brown for a Week

So I had surgery on my tailbone for a cyst back on the 13th, and when I got home I started spotting pink and I thought it was from the surgery, but my doc confirmed that those areas are separate and shouldn't be bleeding. Called my GYNO and they said they couldn't tell me without a culture test. So far I've gotten that it could be because of my nuvaring, bacterial infection (which I always get, but no spotting), or I'm pregnant (neg test, I tested too early) but I've only had cramps on my right side for not even 10 minutes one day and that was it. So my question is why have I been spotting pink and brown for a week when I still have alittle bit until my period comes.