If you are having abnormal bleeding- several things could be causing it, and likely- it's not your cycle. There are hormone issues that can cause bleeding, infections, and other things- not necessarily pregnancy related either. It's pretty rare for a pregnancy to occur when your tubes are tied (although not impossible). I'd just give your doctor a call to see if they can get you in for an exam- they are the best resource since they can gather, or have, more of your medical history and ask more questions- which will get you a more accurate answer.
There is no pain at all and now its just mid light brown discharg