Spotting when wipe with cramps

I normally have regular periods that are typically three days of heavy bleeding and maybe two days of spotting at end.. last month I only bleed for one day (not as heavy as normal) and spotted for two days and I was supposed to start sometime between last Sunday and Wednesday. Yesterday I started spotting brown ( mainly when I wiped) and last night stared having cramps like AF was coming well I'm still spotting.. brown this morning then mid day it was a brownish orangish color with alot of mucus looking discharge, then seen this afternoon a dark blood but it's basically only when I go to bathroom maybe a little on pantiliner every couple hours. one time tonight after using bathroom there was stringy red discarge with what looked like tissue in toilet and when I wiped. Any idea at what could going on? This has never happened to me before.

(I had a tubal ligation in 2014 & have endometriosis)