What Could Causes Very Light Periods?

I am 34 years old...5ft3, and weight about 142 lbs. I had a period about 3 weeks ago that lasted for 3 days. The cramps usually only last for the 1st day, however, this last time, they lasted for over a week and was only cramping on the right side for the duration of that time. I have since then, stopped cramping but am still bleeding. I only bleed when I wipe, its not enough to get a whole lot on my underwear, if any at all. I only really notice the bleeding in the first part of the day, and then it goes away. It doesnt look like a period blood. It looks more like a bloody type of mucus or something. I had my tubes tied about a year ago also, if that helps any.