What Causes Excess Periods With Light Bleeding And Mucus?

I have gotten my period everyother week for the last 2 1/2 months. I had my tubes tied 2 years ago after our 3rd child. Before these last 2 1/2 months I always had regular periods. I have felt nauses now for 3 days... When I have gotten these periods, it has been light and kind of a mucus like substance...