Brown, stringy discharge after miscarriage. Is it normal??

I started bleeding and cramping on Monday, September 19. It wasn't really heavy but it wasn't light either. I felt like I was on my period. On September 22, I went in for my 8 week scan. I was told the baby measured about 6 weeks, there was no heartbeat, the gestational sac was deformed, and the yolk sac was collapsing. (I was already expecting to miscarry because I was measuring behind by a week and the baby's heartbeat was only 87bpm at my 7 week scan). I was told I should be able to miscarry naturally. They drew my blood after the scan and called me later that day to tell me the results. My HCG beta level was 129. I didnt bleed or cramp a whole lot after my 8 week scan. I went back on the 30th to check my hormone levels. My HCG beta that day was 4. I was told to expect a period in 2-3 weeks. I stopped bleeding and cramping for awhile. On Friday, I had some fairly bad cramps, lower back pain, and what felt like really bad heartburn. I also noticed that I have been having dark brown, stringy discharge and some brown spotting. Is this normal after a miscarriage? For my HCG levels to have dropped back down to negative, my body would have had to pass everything, right? I don't remember seeing any huge blood clots.