I Had My Tubes Tied After My Second Child In

I had my tubes tied after my second child in 2013 I have had regular periods up until now...I had my period like normal the week before Sept. 1st...now since 3-4 days after my period stopped I have had what looks like dried blood discharge for the last 2 weeks...me and my boyfriend are intimate regularly ? What could be the cause of this extended period/dry blood colored discharge for the last 2 weeks?